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Disease, Pests and Problems


All vegetable gardens will have problems involving diseases, pests and cultural conditions. This is why it is so important to visit the garden daily during the growing season, allowing early intervention.


The best approach is to use the IPM (Integrated Pest Management) principles. This is a technique which focuses on careful monitoring and early prevention of pests or their damage using a combination of techniques such as biological control, cultural practices and selection of resistant varieties. Pesticides are used only after monitoring indicates they are needed according to established guidelines, and treatments are made with the goal of removing only the target organism. Pest control materials are selected and applied in a manner that minimizes risks to human health, beneficial and non-target organisms, and the environment.


Review the references outlined in the “Vegetable Information” page and also look at the “Herbicide Page” of this website for helpful information.


When confronted with a problem, either call the OSU Master Gardeners, or, ideally, bring an involved sample to the Tulsa County OSU Extension office

Which is open weekdays from 9 to 4 p.m. at 4116 E. 16th Street. The telephone number is 918-746-3701.



Common Garden Problems 



Possible Causes

Corrective Measures

Plants stunted in growth; yellow colored foliage.

Lack of soil fertility or abnormal

 soil pH 

Use fertilizer and correct pH according to soil test.




Use 2 to 3 pounds of complete fertilizer per 100 square feet in absence of soil test.


Plants growing in compacted, 

Modify soil with organic matter,   


poorly drained soil

coarse sand.  Provide surface drainage.



Insect or disease damage;  Root Knot Nematode

Use recommended control treatments.


Iron deficiency

Apply iron to soil or foliage.  Correct soil pH.

Plants stunted in growth;purplish colored leaf veins.  

Low temperature

Plant at proper time. Do not use light-colored



mulch too early in the season.


Inadequate phosphorus

Apply phosphorus at soil test recommendation.

Holes in leaves; leaves yellowish and drooping, or distorted in shape.

Damage by insects

Use recommended insecticide treatment.

Plant leaves with spots; dead, dried areas; or powdery or rusty areas.

Plant disease

Use resistant varieties, remove diseased plants



when noticed and use recommended control




Plants wilt even though sufficient water is present.

Soluble salts too high

Have soil tested.



Poor drainage and aeration


Add organic matter or sand; ridge soil for surface drainage.  Plant in raised beds.


Insect, disease, or nematode 

Use recommended varieties and recommended



damage on roots


treatments of insecticides and fungicides, and soil insecticides or nematicides.

Plants tall, spindly,  and unproductive.

Excessive shade

Relocate to sunny area. Keep down weeds.


Excessive nitrogen

Reduce applications of nitrogen.

Blossom drop (tomatoes).


Hot winds, dry soil


Use mulch and water.

Plant heat tolerant varieties.


Low night temperatures

Avoid early planting.



Overwatering or disease


Reduce watering, use recommended disease control treatments.

Tomato leaf roll.

Excess nitrogen and water

Withhold nitrogen, reduce watering.


Curly top disease of beets

Remove plant if diseased.

Downward cupping and 

2,4-D damage

Don’t spray on windy days or when

curling of tomato leaves.


temperature is above 80°F.

Leathery, dry, brown blemish on the blossom end of tomatoes, peppers, and watermelons.

Blossom end rot

Maintain uniform soil moisture and apply



Avoid overwatering and excessive nitrogen.



Select tolerant varieties.