Weed and Disease Problems

in Soybean

Tomislav Duvnjak

Agricultural Institute Osijek

CROATIA

Danube Soya Innovation and Research: Current status and future plans, 7th May 2015, Berlin

WEEDS

Outstanding competitors to cultivated plants in terms of

space, water, nutrient as well as light

Presented everywhere and more resistant than cultivated

plants (high or low temperatures, drought, long and heavy

moisture/rain, etc.)

Cause losses by reducing yields through interference

(competition) by lowering crop quality and by hindering

harvest.

Weeds can be most effectively managed in soybeans with a

well-planned program:

• a thorough analysis of the field situation,

• use of a combination of cultural practices,

• use of appropriate herbicides.

The most effective weed control system depends of:

• kinds of weeds in the field

• soil characteristics,

• tillage practices,

• crop rotation,

• and soybean row width.

Broadleaf weeds

Ambrosia artemisiifolia

Amaranthus retroflexus

Amaranthus hybridus

Abutilon theophrasti

Capsella bursa-pastoris

Chenopodium polyspermum

Chenopodium album

Datura stramonium

Fallopia convolvulus

Galinsoga parviflora

Hibiscus trionum

Matricaria chamomilla

Polygonum lapatifolium

Polygonum persicaria

Sinapis arvensis

Solanum nigrum

Sonchus asper

Sochus oleraceus

Stellaria media

Veronica agrestis

Veronica persica

Xanthium strumarium

Grass weeds

Echinocloa crus-galli

Setaria glauca

Setaria viridis

Digitaria sanguinalis

Panicum

dichotomiflorum

Panicum capillare

Broadleaf weeds

Cirsium arvense

Cichorium intybus

Convolvulus arvensis

Symphytum officinale

Daucus catora

Lathyrus tuberosus

Rumex obtusifolius

Sonchus arvensis

Calystegia sepium

Grass weeds

Sorghum halepense

Agropyron repens

Cynodon dactylon

Poa pratensis

ANNUAL PERENNIAL

Chemical weed treatment

pre-sowing

pre-emergence

post-emergence

broadcast applied

band applied

Agricultural management

Crop rotation

Inter-row cultivation

The bottom line of any weed management decision is cost.

Aplying band rather than broadcast herbicide and cultivate

once, annual savings on 100 ha could be 1100 – 2650 Euro.

Helps avoid development of herbicide-resistant weeds.

Inexpensive way to control weeds that escape broadcast

treatment.

Commonly used in row crop production (combined with a band of herbicide

applied over the crop row).

Inter-row cultivation can be a means to reduce herbicide use.

Benefit – the most attributed to weed control, also improved soil aeration and

reduced soil compaction, may increase available water.

Soybean injury can occur with certain herbicides,

particularly when stressed from adverse environmental

conditions.

Certain additives can enhance injury from postemergence

herbicides.

Herbicides persistence in soil and potential injury to

rotational crops.

Ambrosia

artemisiifolia

Ambrosia

artemisiifolia

Abutilon theophrasti

Xanthium strumarium

Sorghum halepense

Amaranthus retroflexus

Convolvulus arvensis

Solanum nigrum

Important role in in disease epidemiology in all branches of

plant production.

Weeds enables pathogen survival in extreme environmental

conditions and in absence of the main host for several years.

As alternative hosts, connect vegetation years, host and

locations – epidemiological or green bridges.

“Parasite mycopopulation of weeds in row crops”

“Role of weeds in epidemiology of diseases of row crops”

Abutilon theophrasti: Wild host for three fungal parasites of soybean

First Report of Phomopsis longicolla on Cocklebur ( Xanthium

strumarium ) in Croatia

Xanthium strumarium L. as the host to the fungi Sclerotinia

sclerotiorum (Lib.) de Bary

DESEASES

Fungal

Bacterial

Viral

Nemathodes

More than 100 pathogens are known that affect soybean,

about 35 are importan economically.

All plant parts are susceptible to a number of pathogens:

seed rots and seedling diseases, foliar diseases, root and stem

diseases.

Reduces quality and quantity of grain yield.

Often reduces soybean yield.

As number of hectares under soybean increase, increase the

number and severity of soybean diseases.

The economic importance of any single disease may vary

from one geographic area to another in any one season.

Conservative estimation of worldwide losses to all soybean

diseases is about 11% of the amount produced.

HOST

total of characteristics favouring susceptibility

Bacterial diseases

Bacterial blight Pseudomonas amygdali pv. glycinea

Bacterial pustules Xanthomonas axonopodis pv. glycines

= Xanthomonas campestris pv. glycines

Bacterial tan spot Curtobacterium flaccumfaciens pv. flaccumfaciens

= Corynebacterium flaccumfaciens pv. flaccumfaciens

Bacterial wilt Curtobacterium flaccumfaciens pv. flaccumfaciens

Ralstonia solanacearum = Pseudomonas solanacearum

Wildfire Pseudomonas syringae pv. tabaci

Viral diseases

Alfalfa mosaic genus Alfamovirus, Alfalfa mosaic virus (AMV)

Bean pod mottle genus Comovirus, Bean pod mottle virus (BPMV)

Bean yellow mosaic genus Potyvirus, Bean yellow mosaic virus (BYMV)

Brazilian bud blight genus Ilarvirus, Tobacco streak virus (TSV)

Cowpea chlorotic mottle genus Bromovirus, Cowpea chlorotic mottle virus (CCMV)

Mung bean yellow mosaic genus Begomovirus, Mung bean yellow mosaic virus (MYMV)

Peanut mottle genus Potyvirus, Peanut mottle virus (PeMoV)

Peanut stripe genus Potyvirus, Peanut stripe virus (PStV)

Peanut stunt genus Cucumovirus, Peanut stunt virus (PSV)

Soybean chlorotic mottle genus Caulimovirus, Soybean chlorotic mottle virus (SbCMV)

Soybean crinkle leaf genus Begomovirus, Soybean crinkle leaf virus (SCLV)

Soybean dwarf genus Luteovirus, Soybean dwarf virus (SbDV)

Soybean mosaic genus Potyvirus, Soybean mosaic virus (SMV)

Soybean severe stunt genus Nepovirus, Soybean severe stunt virus (SSSV)

Tobacco ringspot = bud

blight genus Nepovirus, Tobacco ringspot virus (TRSV)

Fusarium spp.

(Peronospora manschurica) Downy mildew

Sclerotinia blight

White mold

Sclerotinia sclerotiorum

Soybean cyst nematode

(SCN),

Heterodera glycines

Phomopsis longicolla (PL)

Phomopsis seed decay

Diaporthe phaseolorum var. caulivora (DPC)

Stem canker

Diaporthe phaseolorum var. sojae (DPS)

Pod and stem blight

DIAPORTHE/PHOMOPSIS Complex (D/P)

on soybean in Europe

Different field damage