|Swelling of leaf cells due to retention of water|
Oedema in plants is the extended swelling in plant organs caused primarily by an excessive accumulation of water. This occurs since the cell walls are composed of flexible cellulose. Mildly affected plants often recover from edema, putting out symptomless new growth, with the arrival of more favorable growing conditions in late spring and early summer.
Symptoms of edema appear as bumps or blisters initially on the undersides of lower or older leaves on a plant. They may then turn brownish or tan and become corky. Severely affected leaves will often turn yellow and fall off the plant. The corky spots sometimes resemble spider mite or thrips damage.
Use a well drained growing medium. Increase light intensity by spacing plants farther apart. Avoid over-fertilizing plants, especially when the plants are growing slowly and avoid growing cultivars that are highly susceptible. Do not over water, and keep plants on the "dry side" during extended periods of low light and cool temperature. Water when air temperature is rising or humidity is low.
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|Adverse conditions||Bruising · Frost · Greening · Magnesium deficiency · Nitrogen deficiency · Oedema · Potassium deficiency · Soft tubers · Spindly sprouts · Split roots · Sun scald|
|Diseases||Alfalfa mosaic virus · Andean potato latent virus · Bacterial soft rot · Black dot · Blackleg · Black potato blight · Alternaria brown spot · Common scab · Dry rot · Early blight · Fusarium wilt · Gangrene · Late blight · Potato deforming rust · Potato leaf roll virus · Potato spindle tuber viroid · Potato virus Y · Potato yellow dwarf virus · Potato yellow vein virus · Powdery scab · Rhizoctonia solani · Ring rot · Septoria leaf spot · Silver scurf · Skin spot · Southern blight · Southern bacterial wilt · Tobacco ringspot virus · Tomato spotted wilt virus · Verticillium wilt · Wart disease|
|Pests||Aphid · Capsid bug · Keeled slug · Leaf miner (Pea leafminer) · Potato cyst nematode · Potato psyllid · Potato rot nematode · Root-knot nematode · Rosy rustic moth · Wireworm|
|Adverse conditions||Blossom drop · Blossom end rot · Catfacing · Dry set · Fasciation · Frost · Greenback · Hollow fruit · Leaf roll · Leggy plants · Magnesium deficiency · Nitrogen deficiency · Oedema · Phosphorus deficiency · Potassium deficiency · Split fruit · Sun scald · Tomato stem primordia|
|Pests||Aphid · Cabbage whitefly · Flea beetle · Greenhouse whitefly · Leaf miner (Tomato leafminer, Vegetable leafminer) · Potato cyst nematode · Potato psyllid · Root-knot nematode · Slug · Thrips (Eastern flower thrips)|