Using The Plant Disorder Diagnostic Key By Paul

Using The Plant Disorder Diagnostic Key By Paul A. Thomas, and Bodie V. Pennisi Department of Horticulture, College Of Agricultural and Environmental Sciences

There’s Always More Than One Problem ! High Heat, Low Fertility, High Irrigation High Light Levels Dry Winds

Unopened Buds Temperature Humidity Light levels Natural Gas Insecticides Manganese Mites Thrips

Fully Opened Flowers Temperature Humidity Light levels Insecticides Natural Gas Botrytis Virus

Growing Meristem Boron Calcium Ethylene Natural Gas Cyclamen mites Thrips

New / Soft Growth Trace Elements Nickel Calcium Light Levels Cyclamen mites Thrips Propane Natural Gas Herbicides

Newly Matured Leaves Temperature Humidity Light levels Potassium Phosphorus

Mature/Older Leaves Temperature Humidity Light levels Spacing Nitrogen Phosphorus Magnesium Potassium Fluoride

Whole Plant Disorder Temperature Humidity Light levels Spacing Nitrogen Soil p. H Sloil EC

Below Soil Disorder Temperature Humidity Light Levels Disease Drought Anoxia Insects

General Disorders

Using The Plant Diagnostic Key A diagnostic key is a tool used to differentiate between many possible, yet similar looking symptoms. Diagnostic keys are simple to use, and can significantly speed up the diagnosis process. However, no key can replace actual diagnostic testing. Always test to verify assumptions before implementing any treatments.

Using The Diagnostic Key The diagnostician must first decide how to describe the problem. Several descriptive words should be written down prior to reviewing the many choices provided in the key.

Using The Diagnostic Key Cleared Tissue Blackening Dessicated Wilted Shiny

There are several categories or approaches to choose from, depending on the extent of the problem, or the plant parts that are expressing symptoms of a disorder. Problems Involving ENTIRE Crop With or Without Pattern Problems Involving WHOLE PLANT With Normal Shape Leaves And Stems. Problems That Appear To Primarily Involving LEAVES, Secondarily Flowers Problems Involving FLOWERS Problems Involving ROOT SYSTEMS

Under each category, there are several choices to choose from. Problems That Appear to Primarily Involve LEAVES and to a Lesser Extent, Flowers. A. LEAF SHAPE ABNORMAL, twisted, or physically damaged stems, internodes normal. AA. LEAF SHAPE NORMAL, internode length normal, but leaves off-color, cleared or have spots. AAA LEAF SHAPE NORMAL, however, stem internodes are very long or very short. AAAA Leaf shape normal, stem internodes normal. Stems severed / broken at soil line. AAAAA. Leaf puckered or with expanded cells, galls, thickening of epidermis. The three sub-choices are marked A, AA , and AAA as they are all related to the category, however, they denote different possibilities from which we may decide on the best fit to our described symptoms. Underneath “AA” are the next level of choices.

These additional choices, marked B, and BB, allow us to further refine our choices, and focus in on the problem. AA. LEAF SHAPE NORMAL, internode length normal, but leaves off-color, cleared or have spots. B. Leaf color in a small portion of the leaf is abnormal. BB. Leaf color over a majority of the leaf surface is abnormal.

Next, we note the best fit sub-category. AA. Leaves appear normal shape, discrete parts of plant are off-color, cleared or wilted. BB. Leaf color over a majority of the leaf surface is abnormal. C. Entire plant pale green, poor growth with some marginal yellow at the margins, few blooms, small flowers. Fungicides, Herbicides Nutritional Deficiencies (Check roots for damage. ) CC. CCC. Entire plant or most leaves yellow, with central portions of the leaf strongly affected. Tissue dies within 3 to 10 days. Entire plant or most leaves turn dark black-green, semi transparent to light, wilt, then die within 48 hours. Herbicides / Sunscald Surfactant / Soaps Chlorine, Petroleum fuels)

Next, we note the best fit possibilities That we should look into. AA. Leaves appear normal shape, discrete parts of plant are off-color, cleared or wilted. BB. Leaf color over a majority of the leaf surface is abnormal. C. Entire plant pale green, poor growth with some marginal yellow at the margins, few blooms, small flowers. Fungicides, Herbicides Nutritional Deficiencies (Check roots for damage. ) CC. CCC. Entire plant or most leaves yellow, with central portions of the leaf strongly affected. Tissue dies within 3 to 10 days. Herbicides / Sunscald Entire plant or most leaves turn dark black-green, semi transparent to light, wilt, then die within 48 hours. Surfactant / Soaps Chlorine, Petroleum fuels)

Occasionally, the diagnostician is directed to check additional areas as many plant problems have more than one cause. BB. Leaf color over a majority of the leaf surface is abnormal. C. Entire plant pale green, poor growth with some marginal yellow at the margins, few blooms, small flowers. Fungicides, Herbicides Nutritional Deficiencies (Also: Check roots for damage. ) CC. CCC. Entire plant or most leaves yellow, with central portions of the leaf affected. often dies within 3 to 10 days. Herbicides / Sunscald Entire plant or many leaves turn dark black-green, semi transparent to light, then die within 48 hours. Surfactant / Soaps, Oils, Chlorine, Petroleum

Nutritional Disorders

Plant Nutrient Functions, Deficiency and Nutrient Management Self-Study Course Toxicity Symptoms http: //www. montana. edu/wwwpb/pubs/mt 4449. html#9 An Excellent Publication!

Nitrogen Entire plant light green or yellow. No necrotic spotting or striping

Phosphorus Purple or reddish discoloration. Prominent on undersides. Leaves slightly smaller, darker green.

Potassium No interveinal chlorosis, Chlorotic areas with burnt leaf margins, or spottong along leaf

Calcium Young leaves increasingly smaller, bunched, hooked may turn brown and die back. Buds may or may not be affected

Magnesium General chlorosis with interveinal chlorosis Leaves sometimes have red, yellow or necrotic spots.

Sulfur Young leaves light green. No chlorotic spotting or striping

Boron New growth twisted, bunched up. Leaves thicker, rolled or stiffened, brittle. Meristem dies back

Nickel Mouse Ear or dwarf leaves. Some darkening of the leaf. Crinkled leaves.

Iron Sharp interveinal chlorosis. Leaves full size.

Manganese Interveinal chlorosis. Stunted growth. Necrotic spots.

Molybdenum Pale, light green leaves Leaves scorched, rolled or twisted

Zinc Middle leaves with interveinal chlorosis.

Copper Yellow leaves. Tips of leaves withered. Leaf tips eventually die.

Chloride No interveinal chlorosis, Chlorotic and necrotic lesions with abrupt boundary between dead and living tissue

So how do we really know?

Soil Analysis N as NH 4+ N as NO 3 - 20 or less (avoid above 40 ppm 160 - 60 ppm Element Parts per Million P K Ca Mg S Fe Mn Zn Cu B 30 - 5 ppm - lower is better! 200 - 40 ppm 160 - 40 ppm 100 - 60 ppm 75 - 100 ppm 0. 3 - 3. 0 ppm 0. 1 - 0. 3 ppm 0. 05 - 0. 5 ppm

Foliar Analysis N P K Zn Ca Cu Mg Mn Fe B S Mo Na Al Percentage 2. 72 - 6. 28 0. 28 - 0. 64 1. 88 - 3. 48 30 – 51 0. 93 - 1. 13 Parts Per Million 6 – 16 0. 32 - 0. 78 135 – 302 72 – 277 21 – 49 0. 22 - 0. 50 0. 14 - 0. 46 0. 01 - 0. 156 34 - 136

Fixing Deficiencies Post-planting amendments for common deficiencies: Material Rate ( Oz / 100 gal of water) Magnesium sulfate 32 oz. Every 3 weeks Calcium nitrate 32 oz. Every 3 weeks Iron sulfate* 1. 0 oz. 1 application * *Excess can cause leaf spotting and problems