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Crinipellis perniciosa Witch's brooms on Downy Birch , caused by the fungus Taphrina betulina A Witch's broom is a disease or deformity in a woody plant , typically a tree , where the natural structure of the plant is changed. A dense mass of shoots grows from a single point, with the resulting structure resembling a broom or a bird's nest . One example of this would be cytokinin , a phytohormone , interfering with an auxin-regulated bud. Usually auxin would keep the secondary, tertiary, and so on apexes from growing too much, but cytokinin releases them from this control, causing these apexes to grow into witch's brooms. Witch's broom growths last for many years and can be caused by many different types of organisms, such as fungi , insects , mistletoe , dwarf mistletoes , mites , nematodes , phytoplasmas and viruses . [1] Human activity is sometimes behind the introduction of these organisms; for example when a person prunes a tree improperly, leaving the tree susceptible to disease. Witch's brooms occasionally result in desirable changes. Some cultivars of trees, such as Picea orientalis 'Tom Thumb Gold', were discovered as witch's brooms. If twigs of witches' brooms are grafted onto normal rootstocks, freak trees result, showing that the attacking organism has changed the inherited growth pattern of the twigs. [1] Witch's brooms are used by various animals for nests including the northern flying squirrel [1] http://en.wikipedia.org/wiki/Witch's_broom Ecology The waboom forms part of South Africas fynbos vegetation and lives up to expectations with its adaptations to fire. The tree-like forms are protected by an

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Page 1: Witch Broom

Crinipellis perniciosa

Witch's brooms on Downy Birch, caused by the fungus Taphrina betulina

A Witch's broom is a disease or deformity in a woody plant, typically a tree, where the natural structure of the plant is changed. A dense mass of shoots grows from a single point, with the resulting structure resembling a broom or a bird's nest.

One example of this would be cytokinin, a phytohormone, interfering with an auxin-regulated bud. Usually auxin would keep the secondary, tertiary, and so on apexes from growing too much, but cytokinin releases them from this control, causing these apexes to grow into witch's brooms.

Witch's broom growths last for many years and can be caused by many different types of organisms, such as fungi, insects, mistletoe, dwarf mistletoes, mites, nematodes, phytoplasmas and viruses.[1] Human activity is sometimes behind the introduction of these organisms; for example when a person prunes a tree improperly, leaving the tree susceptible to disease.

Witch's brooms occasionally result in desirable changes. Some cultivars of trees, such as Picea orientalis 'Tom Thumb Gold', were discovered as witch's brooms. If twigs of witches' brooms are grafted onto normal rootstocks, freak trees result, showing that the attacking organism has changed the inherited growth pattern of the twigs.[1]

Witch's brooms are used by various animals for nests including the northern flying squirrel [1]

http://en.wikipedia.org/wiki/Witch's_broom

Ecology The waboom forms part of South Africas fynbos vegetation and lives up to expectations with its adaptations to fire. The tree-like forms are protected by an exceptionally thick layer of bark. Plants of the small form will survive fire by resprouting from an underground bole. Seeds are stored on the plant in seedheads; once they dry out they release the seeds which are dispersed by wind. Flowers are pollinated by birds. Proteaceae sport proteoid roots which serve to enlarge the surface area for absorption of nutrients and water from the soil through many hair-like structures. No symbiotic relationship is known and it is thought that these proteoid roots do not allow mycorrhiza to form.

Witch's broom is a disease or deformity where the natural structure of the plant is changed. A mass of shoots grow from a single point, with the resulting structure resembling a broom. In the past superstitious events were blamed on witchcraft and the broom-like appearance of this disease has led to its common name. Witch's broom growth may last several years and can be caused by fungi, insects, mistletoe, mites, nematodes, viruses or environmental factors such as pruning. 41 Protea species, including P. nitida, are recorded to be susceptible to witch's broom.

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http://www.plantzafrica.com/plantnop/proteanitida.htm

First Report of Witches’-Broom Disease in a Cannabis spp. in Chinaand Its Association with a Phytoplasma of Elm Yellows Group(16SrV). Y. Zhao, Q. Sun, R. E. Davis, and I.-M. Lee, Molecular PlantPathology Laboratory, ARS-USDA, Beltsville, MD 20705; and Q. Liu,Shandong Institute of Pomology, Taian, P.R. China, 271000. Plant Dis.91:227, 2007; published on-line as DOI: 10.1094/PDIS-91-2-0227C.Accepted for publication 15 October 2006.Hemp fiber plants (Cannabis spp.) spread naturally in almost everyclimate zone in China and have a long history of cultivation in the country(1). While hemp stalks provide high-quality fibers for making ropes, clothes,and paper products, hemp seeds are a rich source of edible oil. During thesummer of 2004, a disease characterized by witches’-broom symptoms wasobserved in wild hemp fiber plants growing in suburban Taian, Shandong,China. The diseased plants developed clusters of highly proliferatingbranches with much shortened internodes and leaves on the affectedbranches were significantly reduced in size. Phytoplasma infection wassuspected in this hemp fiber witches’-broom (HFWB) disease because of thetypical symptoms and because of its geographic location where otherphytoplasmal diseases such as jujube witches’-broom (JWB), paulowniawitches’-broom (PaWB), paper mulberry witches’-broom (PMWB), and

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Chinese wingnut witches’-broom (CWWB) diseases were previouslyreported (3,4). Total DNA was extracted from leaves of four diseased andfour nearby healthy looking hemp fiber plants. Nested PCR were carried outon the DNA samples using phytoplasma universal 16S rDNA primers(P1A/16S-SR and R16F2n/R16R2) (2). Results revealed that all examineddiseased plants were infected by phytoplasma, whereas nearby healthylooking plants were phytoplasma free. Subsequent restriction fragmentlength polymorphism (RFLP) analysis of the PCR-amplified 1.25-kb 16SrDNA R16F2n/R16R2 fragment indicated that the phytoplasma associatedwith HFWB disease belongs to subgroup 16SrV-B of the elm yellows (EY)phytoplasma group. Nucleotide sequence analysis of the cloned HFWBphytoplasma partial rRNA operon (GenBank Accession No. EF029092),spanning a near full-length 16S rRNA gene and a partial 16S-23S rRNAintergenic spacer, suggested that HFWB phytoplasma is most closely relatedto JWB and PMWB phytoplasmas, both members of subgroup16SrV-B. Tofurther characterize the HFWB phytoplasma, a genomic segment coveringfull-length ribosomal protein genes rplV and rpsC was PCR-amplified usingprimer pair rp(V)F1A/rp(V)R1A (2), cloned, and sequenced (GenBankAccession No. EF029093). The nucleotide sequence of the HFWBphytoplasma rplV and rpsC locus is nearly identical (99.9%) to that of JWBphytoplasma. To our knowledge, this is the first report of a phytoplasmaldisease in Cannabis spp. Since HFWB and JWB phytoplasmas shareextremely high sequence identity and share the same eco-geographiclocation, further investigation is warranted to determine whether these twophytoplasmas are actually one species that can infect both plants, an issuehaving important implications in managing both diseases.References: (1) S. Hong and R. C. Clarke. J. Int. Hemp Assoc. 3:55, 1996. (2) I. M.Lee et al. Int. J. Syst. Evol. Microbiol. 54:337, 2004. (3) Q. Liu et al. Plant Dis.88:770, 2004. (4) Q. Liu et al. Plant Dis. 89:529, 2005. Plant Disease / February 2007 227.

Witches Broom

Witches broom occurs on a variety of Proteaceae species and is associated with the Eriphyoid mite Aceria proteae. The symptoms are a fine proliferation of small leaves and stems, often with a redder tint than normal leaves, usually leading, after a few years, to the death of the stem. Seedlings are killed and growth and flower production is lowered in adult plants.

http://protea.worldonline.co.za/diseases.htm

Treatment

1. Prune off and burn all proliferating material.

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2. Spray or dust adjacent material with a systemic pesticide.

Phytoplasma (witch broom pathogen)

Phytoplasma are specialised bacteria that are obligate parasites of plant phloem tissue and transmitting insects (vectors). They were first discovered by scientists in 1967 and were named mycoplasma-like organisms or MLOs.[1] They cannot be cultured in vitro in cell-free media. They are characterised by their lack of a cell wall, a pleiomorphic or filamentous shape, normally with a diameter less than 1 micrometer, and their very small genomes.

Phytoplasmas are pathogens of important crops, including coconuts and sugarcane, causing a wide variety of symptoms that range from mild yellowing to death of infected plants. They are most prevalent in tropical and sub-tropical regions of the world. Phytoplasmas require a vector to be transmitted from plant to plant, and this normally takes the form of sap sucking insects such as leaf hoppers in which they are also able to replicate.

Morphology

Being mollicutes, phytoplasmas lack cell walls and instead are bound by a triple layered membrane.[4] The cell membranes of all phytoplasmas studied so far usually contain a single immunodominant protein (of unknown function) that makes up the majority of the protein content of the cell membrane.[5] The typical phytoplasma exhibits a pleiomorphic or filamentous shape and is less than 1 micrometer in diameter. Like other prokaryotes, DNA is free in the cytoplasm.

[edit] Symptoms

A common symptom caused by phytoplasma infection is phyllody, the production of leaf-like structures in place of flowers. Evidence suggests that the phytoplasma downregulates a gene involved in petal formation (AP3 and its orthologues) and genes involved in the maintenance of the apical meristem (Wus and CLV1).[6] Other symptoms, such as the yellowing of leaves, are thought to be caused by the phytoplasma's presence in the phloem, affecting its function and changing the transport of carbohydrates.[7]

Phytoplasma infected plants may also suffer from virescence, the development of green flowers due to the loss of pigment in the petal cells.[8] Sometimes sterility of the flowers is also seen.

Many phytoplasma infected plants gain a bushy or witch's broom appearance due to changes in normal growth patterns caused by the infection. Most plants show apical dominance, but phytoplasma infection can cause the proliferation of auxiliary (side) shoots and an increase in size of the internodes.[8] Such symptoms are actually useful in the commercial production of poinsettia. The infection produces more axillary shoots, which enables production of poinsettia plants that have more than one flower.[9]

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Phytoplasmas may cause many other symptoms that are induced because of the stress placed on the plant by infection rather than specific pathogenicity of the phytoplasma. Photosynthesis, especially photosystem II, is inhibited in many phytoplasma infected plants.[4] Phytoplasma infected plants often show yellowing which is caused by the breakdown of chlorophyll, whose biosynthesis is also inhibited.[4]

[edit] Transmission

[edit] Movement between plants

The phytoplasmas are mainly spread by insects of the families Cicadellidea (leafhoppers), Fulgoridea (planthoppers) and Psyllidae (jumping plant lice) [10], which feed on the phloem tissues of infected plants, picking up the phytoplasmas and transmitting them to the next plant they feed on. For this reason the host range of phytoplasmas is strongly dependent upon its insect vector. Phytoplasmas contain a major antigenic protein that makes up the majority of their cell surface proteins. This protein has been shown to interact with insect microfilament complexes and is believed to be the determining factor in insect-phytoplasma interaction.[11] Phytoplasmas may overwinter in insect vectors or perennial plants. Phytoplasmas can have varying effects on their insect hosts; examples of both reduced and increased fitness have been seen.[12]

Phytoplasmas enter the insect's body through the stylet, move through the intestine, and are then absorbed into the haemolymph.[12] From here they proceed to colonise the salivary glands, a process that can take up to three weeks.[12] Once established, phytoplasmas will be found in most major organs of an infected insect host. The time between being taken up by the insect and reaching an infectious titre in the salivary glands is called the latency period.[12]

Phytoplasmas can also be spread via dodders cascutaceae [13] or vegetative propagation such as the grafting of a piece of infected plant onto a healthy plant.

[edit] Movement within plants

Phytoplasmas are able to move within the phloem from source to sink, and they are able to pass through sieve tube elements. But since they spread more slowly than solutes, for this and other reasons, movement by passive translocation is not supported.[14]

[edit] Detection and Diagnosis

Before molecular techniques were developed, the diagnosis of phytoplasma diseases was difficult because they could not be cultured. Thus classical diagnostic techniques, such as observation of symptoms, were used. Ultrathin sections of the phloem tissue from suspected phytoplasma infected plants would also be examined for their presence.[1] Treating infected plants with antibiotics such as tetracycline to see if this cured the plant was another diagnostic technique employed.

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Molecular diagnostic techniques for the detection of phytoplasma began to emerge in the 1980s and included ELISA based methods. In the early 1990s, PCR-based methods were developed that were far more sensitive than those that used ELISA, and RFLP analysis allowed the accurate identification of different strains and species of phytoplasma.[15]

More recently, techniques have been developed that allow for assessment of the level of infection. Both QPCR and bioimaging have been shown to be effective methods of quantifying the titre of phytoplasmas within the plant.[14]

[edit] Control

Phytoplasmas are normally controlled by the breeding and planting of disease resistance varieties of crops (believed to the most economically viable option) and by the control of the insect vector.[8]

Tissue culture can be used to produce clones of phytoplasma infected plants that are healthy. The chances of gaining healthy plants in this manner can be enhanced by the use of cryotherapy, freezing the plant samples in liquid nitrogen, before using them for tissue culture.[16]

Work has also been carried out investigating the effectiveness of plantibodies targeted against phytoplasmas.[17]

Tetracyclines are bacteriostatic to phytoplasmas, that is they inhibit their growth.[18] However, without continuous use of the antibiotic, disease symptoms will reappear. Thus, tetracycline is not a viable control agent in agriculture, but it is used to protect ornamental coconut trees.[19]

[edit] Genetics

The genomes of three phytoplasmas have been sequenced: Aster Yellows Witches Broom[20], Onion Yellows (Ca. Phytoplasma asteris)[21] and Ca. Phytoplasma australiense[22] Phytoplasmas have very small genomes, which also have extremely low levels of the nucleotides G and C, sometimes as little as 23% which is thought to be the threshold for a viable genome.[23] In fact Bermuda grass white leaf phytoplasma has a genome size of just 530Kb, one of the smallest known genomes of living organisms.[24] Larger phytoplasma genomes are around 1350 Kb. The small genome size associated with phytoplasmas is due to their being the product of reductive evolution from Bacillus/Clostridium ancestors. They have lost 75% or more of their original genes, and this is why they can no longer survive outside of insects or plant phloem. Some phytoplasmas contain extrachromosomal DNA such as plasmids.[25]

Despite their very small genomes, many predicted genes are present in multiple copies. Phytoplasmas lack many genes for standard metabolic functions and have no functioning homologous recombination pathways, but do have a sec transport pathway.[20] Many phytoplasmas contain 2 rRNA operons. Unlike the rest of the Mollicutes, the triplet code of UGA is used as a stop codon in phytoplasmas, rather than to code for tryptophan.[26]

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Phytoplasma genomes contain large numbers of transposon genes and insertion sequences. They also contain a unique family of repetitive extragenic palindromes (REPs) called PhREPS whose role is unknown though it is theorised that the stem loop structures the PhREPS are capable of forming may play a role in transcription termination or genome stability.[27]

[edit] Taxonomy

Phytoplasmas are mollicutes and within this group belong to the monophyletic order Acholeplasmatales.[8] In 1992 the Subcommittee on the Taxonomy of Mollicutes proposed the use of the name Phytoplasma in place of the use of the term MLO (Mycoplasma-like organism) "for reference to the phytopathogenic mollicutes". [28] In 2004 the genus name Phytoplasma was adopted and is currently at Candidatus status[29] which is used for bacteria that can not be cultured.[30] It's taxonomy is complicated by the fact that it can not be cultured and thus methods normally used for classification of prokaryotes are not possible.[8] Phytoplasma taxonomic groups are based on differences in the fragment sizes produced by the restriction digest of the 16S rRNA gene sequence (Called RFLP) or by comparison of DNA sequences from the 16s/23s spacer regions.[31] There is some disagreement over how many taxonomic groups the phytoplasmas fall into, recent work involving computer simulated restriction digests of the 16Sr gene suggest there maybe up to 28 groups[32] where as other papers argue for less groups, but more sub-groups. Each group includes at least one Ca. Phytoplasma species, characterised by distinctive biological, phytopathological and genetic properties. The table below summaries some of the major taxonomic groups and the candidatus species that belong in them

http://en.wikipedia.org/wiki/Phytoplasma

Catch that Witch!

Rosemary Newton Botany Dept UCT

Witches’ broom is a disease that occurs on many members of the genus Protea. The symptoms of the disease are a characteristic thick, bushy growth, consisting of poorly developed shoots with thin stems and minute, often distorted leaves. The "broom" is produced from normally dormant floral or axial buds. Single branches on plants or whole plants can be affected. The growth is formed from excessive bud proliferation. Diseased plants can only be identified by symptom observation, and the physical change of the plant is irreversible.

Infection may take place from the early seedling stage, and thereafter can occur at any time during the life of the mature plant. The cause, or agent, of the disease has not yet been identified, but is thought to be a microscopic mycoplasma-like organism, which remains in the plant throughout its life. Mycoplasmas are bacteria that do not possess cell walls, and are mostly pathogenic in animals and plants. A toxin from these

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mycoplasmas is believed to stimulate the bud to divide and subdivide to form the witches’ broom growth.

The mode of transmission of the disease to other parts of the plant and to other plants is unknown. However it has been suggested that, due to close association, transmission may be with an eriophyid mite (Aceria proteae), that is believed to show specificity for host plants. The mites are colourless, banana-shaped and microscopically small. These mites have been found to occur under bracts in dormant leaf buds, in flower buds (in unopened flowerheads) and in witches’ brooms. Other members of the Eriophyidae are known vectors for plant pathogens. The mite itself is probably dispersed by wind, man, and possibly birds.

Control of the disease in flower farms is most effective by prevention, by ensuring diseased plants are not sold from nurseries, and by mite control, through regular miticide application. Heavily infested adults and diseased seedlings must be destroyed as it is impossible to restore them to economic production. Light infestations on mature plants can be pruned. All infested material should be destroyed by burning, to stop further spread of the disease.

There is still a great deal about witches’ broom that remains a mystery. I have been struck by the patchiness of the disease in nature. Sometimes every plant is infected, sometimes only the rare few. Some Protea species carry heavy loads of the broom, others seem quite unaffected. Even within a plant, it is far from clear how the disease spreads. For example, do infected individuals produce infected seeds?

As part of an honours project, I am trying to determine the extent of the disease and patterns of infection and spread. I am hoping that results may prove useful to Protea growers in understanding the disease, and controlling it more effectively. This is where the assistance of avid amateurs will be invaluable. I am compiling a list of all the species infected by witches’ broom. Does the disease occur on genera other than Protea? Is it confined to only some sections of Protea? Have atlassers observed any interesting patterns which might help explain distribution or transmission of the disease? I’d be very grateful for comments or observations from atlassers, especially lists of species known to have witches’ broom, and their localities.

Please report all sightings of the "witch" to Rosemary Newton, Botany Dept, University of Cape Town, Rondebosch, 7700: FAX (021) 650-4041, or e-mail: RNEWTON@ BOTZOO.UCT.AC.ZA.

Useful References

R. Dorrington 1988. Witches’ broom disease of Protea cynaroides. SAPPEX News 59: 20.

L. Forsberg 1993. Protea diseases and their control. The Queensland Agricultural Journal Reprint: 1-13.

A.C. Myburgh & D. Rust 1971. Witches broom of proteas. Information Bulletin 34. Fruit and Food Technology Research Institute, Stellenbosch. 3pp.

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R.J. Rust & A.C. Myburgh 1976. Heksebesem by proteas. Veld & Flora 62: 21-22.

S.L. van Broembsen 1989. Handbook of Diseases of Cut-flower Proteas. Internatnl Protea Association, Victoria.

If atlassers record the presence of witches' broom on the SRS in the additional remarks, we will forward the data to Rosemary. Please note: this project will have to be completed sometime around September, so exciting data are really required by June at the latest. Exciting data include witches' broom on genera other than the Sugarbushes. Less exciting, but just as important, are where witches' broom occurs on the known hosts - these data are of interest independent of Rosemary's work - so please let us have the data anytime. We have unconfirmed reports of witches' broom-type infections on Ls tomentosum and Ld salignum. We will process existing data for Rosemary and report progress in the next newsletters.

Tony Rebelo

http://protea.worldonline.co.za/p30witch.htm

There are at least 50,000 diseases of crop plants. New diseases are discovered every year. About 15% of the total U.S. crop production is lost annually to infectious diseases despite improved cultivars and disease control techniques. Damage from disease has not been eliminated. Disease-causing organisms (pathogens) multiply and mutate rapidly. They develop genetic resistance to chemical controls and have the ability to infect new hybrids. Good gardening practices and an understanding of plant pathology are the first line of defense against disease.

In this chapter you will learn that plant health is affected by disease and environmental factors.

DEFINITION OF PLANT PATHOLOGY

 The study of plant diseases is known as plant pathology. Infectious diseases are caused by living organisms called pathogens. Noninfectious diseases caused by environmental stress and damage by weather and other environmental factors also will be covered.

 Indirectly, environmental factors that cause a plant to be stressed may result in the plant's gradual decline. Decline results in the plant being more susceptible to disease organisms. Because of this, diagnosing plant diseases can be tricky. The real cause of a problem

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may be the stress factors, with the disease simply being a secondary factor.

 

DISEASE TRIANGLE

Three critical factors or conditions must exist for disease to occur: a SUSCEPTIBLE HOST PLANT, a PATHOGEN, and the right mix of ENVIRONMENTAL CONDITIONS. The relationship of these factors is called the disease triangle.

If only a part of the triangle exists, disease will not occur. Understanding the disease triangle helps us understand why most plants are not affected by the many thousands of diseases that exist.

 

PATHOGEN

Pathogens are microorganisms that cause disease. Because they are living, they are called BIOTIC (bye-AH-tick) agents or causes. Pathogens can be FUNGI (FUN-geye), BACTERIA, VIRUSES, MYCOPLASMAS (MY-crow-plas-mahs) or NEMATODES (KNEE-ma-toads). Each has a different life cycle, which includes an infectious stage.

Most pathogens are host-specific to a particular plant species, genus or family. For instance, blackspot of rose will not attack marigolds or lettuce. Some diseases, such as the powdery mildews, produce similar SYMPTOMS on different plants. However, the fungi involved are usually host-specific. The rose powdery mildew fungus will not infect zinnias or turfgrass or vice-versa.

 

SUSCEPTIBLE HOST

A susceptible host has a genetic makeup that permits the development of a particular disease. The genetic defense against a disease is called disease resistance. This resistance can be physical characteristics of the plant (fuzzy or waxy leaf surfaces), chemical characteristics (enzymes that kill pathogens and lack of enzymes) and growth patterns (ability to block off diseased tissue or outgrow damage).

Plants also may be disease-tolerant. Even though infected with a disease, they can grow and produce a good crop or maintain an

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acceptable appearance. The plant outgrows the disease and symptoms are not apparent or at a damaging level.

It is important to remember that plants labeled as disease-resistant are resistant only to a particular disease. They are not resistant to all diseases. Resistance does not mean immunity. Under extreme circumstances, resistant plants may be infected by the disease to which they have resistance.

For disease to occur, the host plant must be at a stage of development that allows it to be susceptible to infection. For example, damping-off only affects seedlings. Botrytis is primarily a disease of buds, although it also can occur on flowers and leaves. Also, it is important that the pathogen be in a proper stage of its development to infect host plants.

 

ENVIRONMENTAL CONDITIONS

Certain environmental conditions must exist for disease pathogens to cause infection. The specific conditions vary for different pathogens. High moisture and specific temperature ranges, for example, are necessary for many fungal diseases. These conditions must continue for a critical period of time while the pathogen is in contact with the host for infection to occur.

Moisture, temperature, wind, sunlight, nutrition and soil quality affect plant growth. If one of these factors is out of balance for the culture of a specific plant, that plant may have a greater tendency to become diseased. For example, lilacs growing in shade are more likely to be infected with powdery mildew than those growing in full sunlight.

Environmental conditions also affect the growth and spread of disease pathogens. Very dry or wet weather will have an accompanying set of diseases that thrive under these conditions.

MOISTURE

Moisture in the plant environment can include humidity, dew, rainfall or water from irrigation. Moisture is critical to the spread of most plant diseases. Familiar diseases, such as black spot, fireblight and apple scab require moisture to spread to and infect new host plants.

Constantly wet foliage from overhead watering is a condition that promotes disease development. Seedlings grown indoors in soggy,

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unsterilized potting medium and pots are more prone to damping-off, a fungal disease.

TEMPERATURE

Each disease pathogen has a specific temperature range for growth and activity. There are warm-weather and cool-weather diseases. Many powdery mildew diseases are late summer, warmer temperature diseases. Temperature affects how rapidly pathogens multiply.

Soil temperature can also be critical for disease infection. Cool, wet soils promote fungal root diseases. Temperature extremes can cause stress in host plants, increasing susceptibility.

WIND AND SUN

The combination of wind and sun affects how quickly plant surfaces dry. Faster drying generally reduces the opportunity for infection. Wind can spread pathogens from one area to another, even many miles. Wind and rain together can be a deadly combination. Windblown rain can spread spores from infected plant tissue, blowing these pathogens to new host plants.

Sunlight is very important to plant health. Plants that do not receive the right amount of sunlight to meet their cultural requirements become stressed. This may make them more susceptible to infection.

SOIL AND FERTILITY

Soil type can affect plant growth and also development of some pathogens. Light sandy soil low in organic matter favors growth of many types of nematodes. Damping-off disease increases in heavy, cold, water-logged soils. Soil pH affects pathogen development in some diseases. Clubroot of cabbage occurs in soils with a low pH, for example. High soil pH is a factor in the development of scab on potatoes.

Fertility affects a plant's growth rate and ability to defend against disease. Excessive nitrogen fertilization can increase susceptibility to pathogen attack. It causes formation of SUCCULENT tissue and delays maturity. This can contribute to certain patch diseases in lawns. Nitrogen deficiency results in limited growth and plant stress which may cause greater disease susceptibility.

DISEASE CYCLE

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Often gardeners believe that their plants have become diseased overnight. This may be true in the case of damping-off. More often, however, much has occurred before symptoms are seen. There are five stages in disease development: inoculation, incubation, penetration, infection and symptoms.

INOCULATION

The pathogen must be introduced (inoculated) to the host plant. Most pathogens cannot move on their own, but must be carried to the host plant. This is done by rain, wind, insects, birds and people.

Splashing rain carries spores of apple scab fungus from infected apple leaves to uninfected leaves. Wind blows fungal spores from plant to plant. The spotted cucumber beetle transmits bacterial wilt of cucumbers when feeding.

Working in the garden when plants are wet is a common way to spread disease. Disinfesting tools requires a 9-to-1 solution of water and bleach and takes a minimum of ten minutes. Smokers can transmit tobacco mosaic virus from a cigarette to tomato plants.

Seeds or cuttings from infected plants will also transmit disease. Certified seed guarantees that at the time of sale the seeds are free of all diseases. Seeds are often coated with a fungicide to prevent the transmission of surface fungal diseases.

Disease-free stock guarantees that the plant is not infected with disease. This is particularly important with perennial plants, such as roses, raspberries and other small fruits.

INCUBATION

The second stage of disease development is incubation. The pathogen changes or grows into a form that can enter the new host plant. In many fungal diseases, the pathogen arrives on the plant as a spore which must germinate before it can grow into the plant.

PENETRATION

The third stage is penetration or the point at which the pathogen actually enters the host plant. Once the fungal spore germinates, it sends out thread-like tubes call hyphae. These penetrate the plant through wounds or natural pores. Wounding roots of bedding plants during transplanting provides entry for root-rotting fungi. The mouthparts of an insect also result in openings for penetration.

INFECTION

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The fourth stage is infection. The pathogen grows within the plant and begins damaging the plant tissue.

SYMPTOMS

As the pathogen consumes nutrients, the plant reacts by showing symptoms. Symptoms are evidence of the pathogens causing damage to the plant. Symptoms include mottling, dwarfing, distortion, discoloration, wilting, and shriveling of any plant part.

 

PATHOGEN SURVIVAL

Many pathogens can survive without a susceptible host even under the most unfavorable conditions. Many plant diseases survive from one growing season to the next on plant debris, seeds, alternate hosts or in soil.

Because of pathogen survival, it is important to remove and properly dispose of any infected plant materials. It is also important for the gardener to know about the diseases that affect each plant throughout the home landscape, as well as the conditions needed for proper culture.

Check lit:Wieczorek, A.M. and Wright, M.G. 2003. Phytoplasma-induced witches' broom disease on Protea spp. (Proteaceae) and unique arthropod vectors determined by molecular techniques. Acta Horticulturae 602:161-166

Question. MORTALITY IN PROTEAS

Are there any reference to the effect that not much mortality occurs in proteas once they become established?

Answer: This is based on observation. There are exceptions - the Silver Tree has a mortality of about 1-5% per year. Most other proteas have such a low death rate that even 1 or 2 dead plants on a mountain side are very conspicuous and generate comment. Under normal conditions, death rate must be well less than 0.5% per annum. During serious droughts it may reach 10%, although I have seen a population of Ld "touwsrivierensis" at Baviaanskloof where a seep was obviously drying up and almost 60% of the population died - all on the periphery. I have also seen one case of inexplicable mortality, where most species were affected, and survivors contained only live branches on the SE side of the plants - no fire, plenty water, must have been a severe hot wind or (unlikely given the area, but not impossible) a defoliant/herbicide

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brought in on a wind. Restios and fine-leaf dicots were unaffected, but all broad leafed plants were hammered.

OK: SO YOU WOULD SAY THAT MOST MORTALITY OCCUURED ONLY DURING THE FIRST FEW YEARS AFTER ESTABLISHMENT IN THE VAST MAJORITY OF POPULATIONS, UNTIL SENESCENCE MAY KICK IN. HOW OFTEN DO YOU ENCOUNTER HERBIVORY? IS IT QUITE RARE?

Answer: No data, I can only offer my casual field observations. I will check up on some of Henri and Penny Mustarts work though tonight.

Mortality. If it occurs - apart from exceptional drought years, which may (how do you model this?) get more common with global enhanced warming - occurs in year 1. After year 2 until year 30 it is exceptional in most larger proteas. Note that there are exceptions. Serruria florida disappears between years 5 and 8, Orothamnus largely disappears between years 10 and 15. These though are cases of early senescence - make your seeds, put them in ants nests and vanish. Interestingly Orothamnus is gone by ca12 years but "co-exists" with Mi arboreus which is reputed to flower for the first time at 8 years.

Herbivory: what level?

Witches Broom: this Phytoplasma kills branches and young plants, but most species cope with it. It seems to become more prevalent in older veld, and where older veld abuts younger veld and where fires are patchy, but this is an impression and I have no data to support it.

Leaf miners: present all the time, difficult to assess damage.

Leaf feeders: leaves are only available for herbivory as they grow big, before hardening. At this time protea leaves are bright red. Any herbivory results in huge chunks missing from the leaves as the missing chunks enlarge with the leaf - this means that you can calculate the proportion of leaf eaten, but not the actual amount. It is easy to measure this herbivory! - but how do you relate the proportion of leaf to its size when eaten? Only Protea nitida has a major problem in this regard and I have seen thousands of small black beetles heavily eating the bright red leaves: but only locally 2 or 3 times over the past 20 years (sample = Sept-Oct months only when new leaves are produced). Otherwise, leaf predation is almost non-existent.

No indigenous herbivores are recorded eating proteas at Cape of Good Hope Nature Reserve. But cows heavily eat Pr odorata, Pr mucronifolia and occasionally other very young proteas. In heavily overgrazed areas predation by livestock may result in the tops of proteas being chewed off. Protea Atlas Data: We have 551 records of "New Growth": about half of these document aseasonal growth or observations about new growth. Half of the remainder are baboon damage (more below). That leaves about 100-150 (no time to go through them now) records of herbivory out of 250 000 records. Horse pastures feature but mainly for Leucadendrons.

Plant damage: Baboons: baboons damage plants a lot. Accidentally by using proteas as sentry posts they break branches (off!) and damage leading stems so that they die. They also remove flowerheads for eating nectar and insects, and appear - someone must have told me this, where I get the idea from I don't know - to prefer those with grubs in the receptacle. They also very occassionally remove cones from Conebushes.

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Otomys Vlei Rat damage: (I assume Otomys, based on habitat, I am probably wrong). Otomys (mus?) chops off stems of plants at about head height (i.e. 15cm) to get at seeds, flowers and growth tips way above it. This can seriously affect plants (obligate reseeders do not invest in stem buds and once the leaves die those stems cannot regenerate so that if chopped off by Otomys or gardeners, that stem, or in single-stemmed plants - the entire plant, dies). Although I have seen this mainly in Spatalla and Serruria - almost always near vleis, rivers or seeps - it is also recorded for Orothamnus, and it has been proposed (who? my memory fades-old age: Jan Vlok? Charlie Boucher?) that the rapid erect, unbranched growth of Orothamnus is primarily to remove it from predation by Otomys.

 I believe that this is Tony's claim. i.e. that most of the mortality occurs during the establishment after a fire and early growth phases?

Answer: This is assumed. Tony would claim that if there is any mortality, then it will occur during the early growth phases. However, in many situtations there may well be no mortality worth speaking of, or else because plants are small, it is not noticeable. There is some mortality of plants after first reproduction, but it is also small, but enough to generate notable differences in sex ratios in Leucadendron. However, the best bias ratios are in resprouting species.

BUT AGAIN NO ONE HAS DOCUMENTED THIS OR PUBLISHED ON THIS? SEEMS SURPRISING.

Answer: How on earth do you publish the mundane and obvious? Having been brought up in Fynbos the idea of density dependent mortality, self thinning and between fire mortality are concepts confined to the vegetable garden. Even the Pine and Acacia invaders in Fynbos seem not to care about mortality - they just - like proteas at high seedling densities- grow old as thin and weedy runts: and William has shown that seed production per unit area remains constant (until very high densities), even though seed production per plant can be negligible. This is all basic to Fynbos and it is a wonder to go to systems that operate in bizzarre and unreal ways. It takes outsiders to come in and discover the obvious: but then the principles are so obvious they are just mentioned as strategies. We don't have enough scientists here to measure the obvious. Witness all of Guy's wild physiological extrapolations based on 1 (or 2) protea, 1 restio, 1 erica and 1 grass, all of one ecotype over 1 season!

It goes without saying that many of our preconceptions might be wrong!

 The idea here is to help us in laying out demographic models for a set of protea species -- that what is important is reproduction in the population (cumulative or right before the fire) then fire then establishment (with growth and mortality responding to local climate conditions in those years), then just growth and reproduction (little mortality) until the next fire.

Answer: No - after 20-30 years senescence kicks in and mortality increases. By 50-year old veld most adult plants are dead and serotinous seed banks are lost.

There is lots of references to seed germination and that seedling recruitment is confined to a year or two after the fire. On senescence it is much less.

I will look at home for references - Kruger is the most likely.

Plant community Diversity and dynamics in relation to fire. FJ Kruger 1983. 445-472. in Mediterranean-type Ecosystems: the role of nutrients. Eds FJ Kruger, DT Mitchell & JUM Jarvis Springer-Verlag, Berlin.

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In summary: no data on early post fire survival. Extremely little on senescence, but Pr neriifolia declines from 860/1000 at 25 years to 300/1000 at 30 years to 50/1000 at 38 years (unpubl records SA Directorate of Forestry). Minimal mortality until > 25 years is the norm.

Resprouters have 92-100% survival. Specht 1981 (in above) suggests that surface soil moisture content above 80% is important in the first year and then soil moisture is irrelevant and mortality patterns change. But no data for Fynbos on rates of mortality.

 GREAT! BUT SURPRISING TO SEE NO PUBLISHED INFORMATION ON EARLY POST FIRE SEEDLING SURVIVAL.

http://protea.worldonline.co.za/mortality.htm

Francois Roets Lecturer

email: [email protected]: +27 808 2635

Room 1013J.S. Marais BuildingStellenbosch University

   

 

 

Biography

 I obtained my PhD from Stellenbosch University in 2006 where my research focussed on various aspects of the taxonomy and ecology of an unusual group of fungi (ophiostomatoid fungi) that are associated with Protea species and have mutualistic associations with mites (Acari) that disperse their spores. I have a keen interest in all forms of inter-organismal-interactions, with experience in the diverse fields of Entomology, Botany and Mycology. Within these fields I am involved in various disciplines including Molecular Biology, Biodiversity, Ecology, Taxonomy and Evolution.

 CURRENT PROJECTS:

 Mite- Protea -Ophiostomatoid fungi-Beetle interactions

 Ophiostomatoid fungi include some of the world’s best known fungal pathogens of trees (natural and cultivated). Most members are vectored by arthropods. One of the most unusual niches in which these species have been found is within the infructescences of Protea in South Africa. Our research indicated that these fungi are vectored by mites that feed on the fungi they carry, indicating a mutualistic association between these mites and their fungal partners. In turn, the mites are vectored by beetles between Protea populations. To date, numerous undescribed species of ophiostomatoid fungi have been identified. Their ecological role is however still poorly understood. Currently we are expanding research into this system to include studies on the competition between various fungi and possible mutualisms between Proteas and their fungal partners. The influence that humans have (e.g. habitat fragmentation, introduction of new hosts, introduction of similar fungi, etc.) on these intricate interactions is of great interest. Understanding this system may ultimately enhance efforts to control ophiostomatoid fungal invasions in natural and forestry systems.

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 Anther-smuts associated with Oxalis spp.

The smut fungi contain some of the most devastating plant pathogens of commercially produced plants. Some species (e.g. Microbotryum spp.) disrupt plant reproduction by replacing the pollen grains in anthers of infected plants with fungal spores. These spores are then transported between flowers by the usual pollinators. Anther-infecting species are endophytes but do not seem to negatively affect other biological processes within their hosts. Recently, a unique Thecaphora anther-smut species was discovered from Oxalis species (with some 50 rare and/or endangered species) in the Cape Floristic Region. Like Microbotryum spp., this species also produce spores within the anthers of host plants and subsequently induces host sterility. Nothing is currently known about the biology of this species. Investigations involving Oxalis population dynamics and fungal infection rates are of particular interest as these fungi may have a large impact on past and future distributions of Oxalis spp. (especially in light of global warming).

  CapeMycota: An initiative for the study of CFR fungal Biodiversity, Ecology and Conservation

 This initiative was largely brought on by a recent paper by Crous et al. (2006) entitled “How many species of fungi are there at the tip of Africa?” that investigated estimations of fungal diversity in, amongst others, the exceptionally plant diverse Cape Floristic Region (CFR). The study summarised current knowledge of fungal biodiversity patterns in the CFR and highlighted the need for more focussed studies in this floristically diverse area of the globe. A paper by Hyde et al. (2007) entitled “Diversity of saprobic microfungi” dealt with issues surrounding current estimations of global fungal biodiversity and highlighted some problem areas that will need to be addressed in order to make more accurate estimations. We would like to address the issue of using plant diversity as an estimate of fungal diversity by focussing on specific fungal groups that are associated with particular plant species from three prominent and economically important CFR plant families. In order to address some of the limitations highlighted by Hyde et al. (2007) we intend to evaluate fungal biodiversity patterns with relation to the following host factors: phylogenetic placement, architecture, distribution and life history traits. Better estimations of fungal diversity will ultimately lead to better understanding of the total biodiversity losses in natural systems incurred by habitat fragmentation and global warming.  Monitoring anthropogenic impacts on population numbers of the endangered Table Mountain Stag

Beetle ( Colophon westwoodi ).

The genus Colophon currently includes 17 flightless species that are confined to high altitude

mountain peaks in the Western Cape Province of South Africa. Almost nothing is known regarding

the biology of Colophon species. Due to their apparent specialised and narrow niche requirements,

most species in the genus can be considered naturally rare. As a consequence, all species are Red-

listed as endangered or critically endangered, and CITES-listed. Habitat transformation and its

inevitable impact on Colophon population numbers are evident at one of South Africa’s most

popular tourist destinations, Table Mountain. This project aims to determine population size and

range extent of C. westwoodi on Table Mountain in order to make informed conservation

management suggestions. It also aims to determine seasonal variation in numbers and other

ecological factors that influence Colophon population numbers.

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Biodiversity, ecology and evolution of ophiostomatoid fungi associated with native and introduced trees in a global biodiversity hotspot.

Symbioses are extremely important in shaping biological systems. The role of mutualisms is of particular interest as these often allow organisms to take advantage of new, otherwise unsuitable niches. This study aims to evaluate the role of symbiotic interactions between ophiostomatoid fungi, host plants and arthropods in shaping pathogen-host associations in the Cape Floristic Region (CFR), one of the most threatened global floristic kingdoms. The ophiostomatoid fungi include well-known and significant international agricultural and forest pathogens (e.g. Ophiostoma ulmi (the causes of Dutch elm disease) and Ceratocystis fagacearum (responsible for Oak wilt). Non-pathogenic species also colonise trees and timber causing discoloration of the wood that result in large monetary losses to the forestry industry. Thee fungi produce sticky spores on elongated structures that promotes spore dispersal via arthropods. Spore vectors include wood- and sap feeding beetles and mites. The relationships between the vector arthropods and their fungal partners are often mutualistic. The arthropods need the fungi for nutrition and this has led to the evolution of specialised spore-carrying structures in some cases. In addition to transportation to new substrates, the fungi benefit by being actively cared for by the vectors (notably ambrosia beetles) in their “fungal gardens”. The ophiostomatoid fungi-arthropod-plant system now serves as a model system for the study of complex symbioses. However, there is a distinct lack of knowledge on the diversity and ecology of ophiostomatoid fungi on both native and exotic hosts in Africa. The main aim of this study is to investigate the extent of ophiostomatoid fungal diversity in the Cape Floristic Region (CFR) and the determinants that enable these ophiostomatoid fungi to infect new host species.   Mite (Acari) diversity in the infructescences of Protea species

Mites are the primary participants in complex Protea-ophiostomatoid fungi symbioses. They affect host population dynamics as either disease dispersal agents, as fungivores protecting seeds against pathogens or as predators that act as bio-control agents. Mite systematics and ecology, in general and particularly in fynbos, is understudied. This project sets out to investigate the diversity of mites associated with Protea species in the Fynbos Biome by addressing the following key questions a) What environmental and ecological factors influence mite communities within Protea infructescences?, b) Are there any co-evolutionary patterns between these two groups and finally, c) Implications for biodiversity conservation. Preliminary data show that host-associations in specific mite guilds correlate with Protea morphological groupings and may thus indicate co-evolution between these taxa. Three mite genera were recorded from South Africa (Hottentots Holland Mountains) for the first time and a further five new species await description. Mite diversity data obtained in this study is central to determining the key elements of fungus-Protea-mite symbioses and may aid informed conservation decision making in the fynbos biome.

Publication List

Published abstracts

1. Roets F, Dreyer LL, Wingfield MJ, Crous PW. (2007). Ophiostoma species from Protea infructescences: Four way interactions between plants, fungi, mites and beetles. SAAB Abstracts, South African Journal of Botany 73: 309–310.

2. Dreyer LL, Roets F, Wingfield MJ, Begerow D. (2008). Discovery of anther-smut fungi on Oxalis from the CFR. SAAB Abstracts, South African Journal of Botany 74: 366.

3. Theron, N., Dreyer, L.L., Roets, F. & Esler, K.J. 2008. Mite (Acari) diversity in the infructescences of Protea species. SAAB 2008 Abstracts, South African Journal of Botany

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74: 391

4. Suda J, Loureiro J, Travnicek P, Rauchova J, Vit P, Urfus T, Kubesova M, Dreyer LL, Oberlander KC, Wester P, Roets F (2009). Flow cytometry and its applications in plant population biology, ecology and biosystematics: New prospects for the Cape flora. SAAB 2009 Abstracts, South African Journal of Botany 75(2): 389-389

 

5. Theron N, Roets F, Dreyer LL, Esler KJ (2009). Mite (Acari) diversity in the infructescences of three Protea species. SAAB 2009 Abstracts, South African Journal of Botany 75(2): 422-423

 

6. Curran HR, Roets F, Dreyer LL (2009). Primary assessment of Thecaphora anther-smut infection of CFR Oxalis. SAAB 2009 Abstracts, South African Journal of Botany 75(2): 431-432 

 

7. Theron N, Roets F, Dreyer LL, Esler KJ (2009). Arthropod diversity in the infructescences of three Protea species. SAAB 2009 Abstracts, South African Journal of Botany 75(2): 441-441

Published papers

1. Lee S, Taylor, JE, Groenewald JZ, Crous PW, Roets F (2003). Rhyncomatoid fungi occurring on Proteaceae including two new species. Mycologia 95: 902–910.

2. Roets F, Crous PW, Dreyer LL (2005). Seasonal trends in colonization of Protea infructescences by Gondwanamyces and Ophiostoma spp. South African Journal of Botany 71: 307–311.

3. Lee S, Roets F, Crous PW (2005). Biodiversity of saprobic microfungi associated with the infructescences of Protea species in South Africa. Fungal Diversity 19: 69–78.

4. Roets F, Wingfield MJ, Dreyer LL, Crous PW, Bellstedt DU (2006). A PCR-based method to detect Ophiostoma and Gondwanamyces from the surface of insects colonising Protea flowers. Canadian Journal of Botany 84: 989–994.

5. Roets F, de Beer ZW, Dreyer LL, Crous PW, Zipfel R, Wingfield MJ. (2006). Multigene phylogeny of Ophiostoma spp. associated with Protea infrutescenses including two new species. Studies in Mycology 55: 199–212.

6. Roets F, Dreyer LL, Geertsema H, Crous PW. (2006). Arthropod communities in Proteaceae infructescences: seasonal variation and the influence of infructescence phenology. African Entomology 14: 257–265.

7. Roets F, Wingfield MJ, Crous PW, Dreyer LL. (2007). Discovery of fungus-mite mutualism in a unique niche. Environmental Entomology 36: 1226–1237.

8. Roets F, de Beer ZW, Wingfield MJ, Crous PW, Dreyer LL. (2008). Ophiostoma gemellus and Sporothrix variecibatus from mites infesting Protea infructescences in South Africa. Mycologia 100 (3): 496–510

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9. Roets F, Dreyer LL, Begerow D, Wingfield MJ. (2008). Thecaphora capensis sp. nov., an unusual new anther smut on Oxalis in South Africa. Persoonia 21: 147–152

10. Roets F., Léanne L. Dreyer, Pedro W. Crous, Michael J. Wingfield. (2009). Mite-mediated hyperphoretic dispersal of Ophiostoma spp. from the infructescences of South African Protea spp. Environmental Entomology 38(1): 143–152

11. Francois Roets, Michael J. Wingfield, Pedro W. Crous, Léanne L. Dreyer. (2009). Fungal Radiation in the Cape Floristic Region: an analysis based on Gondwanamyces and Ophiostoma. Molecular Phylogenetics and Evolution 51(1): 111–119

12. Leanne Dreyer, Francois Roets, Kenneth Oberlander. (2009) Oxalis saltusbelli: a new Oxalis (Oxalidaceae) species from the Oorlogskloof Nature Reserve, Nieuwoudtville, South Africa. South African Journal of Botany 75: 110–116

13. Cobus Visagie, Francois Roets, Karin Jacobs. (2009) A new species of

Penicillium, P. ramulosum sp. nov., from the natural environment. Mycologia 101

(6): 888–895

 

14. Helen Curran, Francois Roets, Léanne L. Dreyer. (2009) Preliminary

assessment of Anther-smut fungal infection of South African Oxalis species:

spatial distribution patterns and impacts on host fecundity, South African

Journal of Botany: Special issue 75: 807–815

 

15. Francois Roets, Michael J. Wingfield, Brenda D. Wingfield, Léanne L. Dreyer. (2010)

Two new species of Ophiostoma from Protea caffra in Zambia. Persoonia 24:

18–28

 

16. Léanne L. Dreyer, K.C. Oberlander, F. Roets. (2010) Reassessment of the taxonomic status of

Oxalis fabaefolia (Oxalidaceae) and the description of a unique variety of Oxalis flava from the

Northern Cape province of South Africa, Blumea (accepted)

 

17. F. Roets, K.C. Oberlander. (2010) Silvaphilus, a new dung beetle genus from South Africa.

African Entomology 18(2): (accepted)

 

18. K. C. Oberlander, L. L. Dreyer, F. Roets (2010). Rediscovery and taxonomic position of the rare

Oxalis purpurata (Oxalidaceae). Bothalia (accepted)

http://consent.sun.ac.za/profile.php?id=80

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Article structure

Subdivision - numbered sections Divide your article into clearly defined and numbered sections. Subsections should be numbered 1.1 (then 1.1.1, 1.1.2, ...), 1.2, etc. (the abstract is not included in section numbering). Use this numbering also for internal cross-referencing: do not just refer to "the text". Any subsection may be given a brief heading. Each heading should appear on its own separate line.

Introduction State the objectives of the work and provide an adequate background, avoiding a detailed literature survey or a summary of the results.

Material and methods Any species or infraspecific taxon studied is to be referenced against appropriate literature used to identify the material concerned. Give full scientific name(s) of plant(s) used, as well as cultivar (cv.) or variety (var.) where applicable. All growth conditions should be properly described. Sufficient detail of the techniques used should be provided to allow easy repetition.

Results Results should be clear and concise. Do not include material appropriate to the Discussion.

Discussion This should highlight the significance of the results and place them in the context of other work. Do not be over-speculative or reiterate the results. If desired the Results and Discussion sections may be amalgamated.

Appendices If there is more than one appendix, they should be identified as A, B, etc. Formulae and equations in appendices should be given separate numbering: Eq. (A.1), Eq. (A.2), etc.; in a subsequent appendix, Eq. (B.1) and so on. Similarly for tables and figures: Table A.1; Fig. A.1, etc.

Essential title page information

• Title. Concise and informative. Titles are often used in information-retrieval systems. Avoid abbreviations and formulae where possible.• Author names and affiliations. Where the family name may be ambiguous (e.g., a double name), please indicate this clearly. Present the authors' affiliation addresses (where the actual work was done) below the names. Indicate all affiliations with a lower-case superscript letter immediately after the author's name and in front of the appropriate address. Provide the full postal address of each affiliation, including the country name, and, if available, the e-mail address of each author.• Corresponding author. Clearly indicate who will handle correspondence at all stages of refereeing and publication, also post-publication. Ensure that telephone and fax numbers (with country and area code) are provided in addition to the e-mail address and the complete postal address. • Present/permanent address. If an author has moved since the work described in the article was done, or was visiting at the time, a "Present address" (or "Permanent address") may be indicated as a footnote to that author's name. The address at which the author actually did the work must be retained as the main, affiliation address. Superscript Arabic numerals are used for such footnotes.

Abstract

A concise and factual abstract is required. The abstract should state briefly the purpose of the research, the principal results and major conclusions. An abstract is often presented separately from the article, so it must be able to stand alone. For this reason, References should be avoided, but if essential, then cite the author(s) and year(s). Also, non-standard or uncommon abbreviations should be avoided, but if essential they must be defined at their first mention in the abstract itself. It must not exceed 5% of the manuscript.

http://www.elsevier.com/wps/find/journaldescription.cws_home/707238/authorinstructions#25000