Bellringer-October 7, 2104

1) Name 3 different causes of why a plant might become diseased (think hard):

2) What is the difference between biotic and abiotic?

3) For the picture below, list as many observations you can make about this plant.

Aquaponics

Plant Diseases and Deficiencies

Definitions• Plant Pathology – The study of plant diseases• Plant Disease – Any physiological or

morphological change in a plant that results in abnormal appearance or development

• Pathogen – An organism that causes disease• Symptom – Abnormal appearance of a plant• Sign – Appearance of the actual pathogen (fruiting

bodies, spores, hyphae etc.)

Components of a Plant Disease

• Conducive Environment• Susceptible Host• Virulent Pathogen

Disease Classes

• Abiotic (not transmissible) – Caused by something that is not alive, like over-watering– Damage from chemicals, weather, mechanical– Nutritional problems

• Biotic (transmissible) – Caused by something that is alive, like a bacteria– Pathogens-parasitic microorganisms that cause

diseases– Pests-insects, mammals, or other plants feeding on

or damaging plants

Causes of Abiotic Disease

• Environmental – freezing, flooding, drought, light, wind, hail

• Cultural – mechanical damage, planting problems

• Chemical – fertilizers, herbicides, pets• Physiological Disorders – abnormal growth

due to genetic and/or environmental interactions

Causes of Biotic Diseases (Pathogens)

• Fungi• Bacteria• Viruses• Nematodes• Parasitic Plants

How do symptoms progress?• Biotic disease-

symptoms progress and nearby plants become infected.

• Abiotic disease-generally a lack of symptom progression– Exception-nutritional

symptoms progress slowly.

Observe Patterns

Underdevelopment

Overdevelopment

Leaf Spots

• Cause – Fungi, bacteria, insects, mites, or abiotic factors

• Symptoms – Circular yellow or brown and dead spots on the leaf

Fungal Blight• Fungus causes black dead spots on leaves or

fruit• Blight= rapid death or die back

Wilts

• Cause – Fungi or bacteria• Signs and Symptoms – Vascular Plugging,

wilted leaves and shoots

Galls

• Cause – Fungi, bacteria, insects, mites, nematodes, and abiotic factors

• Symptoms – Abnormal proliferation of plant tissue specific to a certain plant part; swelling

Rusts

• Cause – Fungi• Signs and Symptoms – Fungal spore masses on

leaves and stems

Cankers

• Cause – Fungi or bacterial infection resulting in dead, non-growing areas on stems and branches

• Signs and Symptoms – Dark sunken areas with distinct margins on stems

Root Rot

• Cause – Fungi and bacteria• Signs and Symptoms – wilting, stem

discoloration, dead roots

Mildew

• Cause – Fungi• Symptoms – yellowing blotches on leaves,

hyphae and fruiting bodies on surface

Abiotic: Blisters

Plant Deficiencies Definition

• Nutrient shortage or unavailability to plant that results in a physiological reaction

• What are the 9 essential macronutrients?–C, H, O, N, P, S, Ca2+, K+, Mg2+

• Deficiency in nutrients causes specific symptoms

–Ex: yellow leaves without Mg+2

• The most common deficiencies are those of N, K+, and P

Essential Plant Nutrients

Healthy

Phosphate-deficient

Potassium-deficient

Nitrogen-deficient

Symptoms

• Chlorosis - condition in which leaves produce insufficient chlorophyll.

• Chlorophyll is responsible for the green color of leaves, chlorotic leaves are pale, yellow, or yellow-white.

• Necrosis - browning and dieback of leaf edges and tips, sometimes extending into the leaf between the major veins.

• Can be caused by numerous factors that restrict the flow of water to the leaves and lack of nutrients.

Chlorosis

Reddening

Different Soil pH = different nutrient availability

How to Diagnose Deficiencies…

How to Diagnose Deficiencies…

Disease Control

• Select plant material adapted to environment• Buy disease-free seed and healthy plant material.• Plant disease-resistant varieties when available.• Choose plants that fit the site.• Keep plants healthy.• Control PESTS.• Use chemical control with care.

How to fix a deficiency problem

• Check soil pH• Apply a quality general use fertilizer or

manure/compost

Exit Slip-October 7, 20141) List 3 biotic diseases and 3 abiotic diseases.

Explain the cause and appearance of the diseased plant.

2) Describe the symptoms of a plant with the following nutrient deficiency:

a) Nitrogenb) Phosphorus