|A tomato leaf showing typical, phosphorous deficient, purple markings|
Phosphorous deficiency can be caused by a number of factors. It is most common in areas of high rainfall, especially on acid, clay or poor chalk soils. Plants also require warmth to take up the phosphorus in the soil, so cold weather can cause a temporary deficiency.
Symptoms include poor growth, and leaves that turn blue/green but not yellow - oldest leaves are affected first. Fruits are small and acid tasting. Phosphorus deficiency may be confused with nitrogen deficiency. Undersides of tomato plant leaves, and the veins and stems, may turn purple. stiff, stunted plants with purlish tinge. Hello :)
It can be controlled by applying organic sources of phosphorus such as rock phosphate or a high-phosphorus fish fertilizer applied as a soil drench or foliar feed.
Plants that are naturally adapted to low levels of available soil phosphorus, however, are more likely to suffer from phosphate poisoning: the key is to provide the right level for any particular plant type, neither too high nor too low.
- Hanna. (2008). Tomato Seedling 911: Yellow & Purple is not a Fashion Statement. Retrieved: 2010-08-12.
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|Carrot · Celeriac · Celery · Chervil · Coriander · Cumin · Dill · Fennel · Lovage · Parsnip · Parsley · Sweet cicely|
|Adverse conditions||Cavity spot · Stem crack · Forking · Phosphorus deficiency · Split roots|
|Diseases||Aster yellows · Bacterial blight of carrot · Bacterial soft rot · Black rot · Cavity spot · Cercospora leaf spot of carrot · Downy mildew · Powdery mildew · Crown rot · Leaf blight of fennel · Mosaic virus · Phytophthora blight · Pseudomonas syringae · Sclerotinia rot · Septoria leaf spot of celery · Septoria leaf spot of parsley · Violet root rot|
|Pests||Aphid · Carrot fly · Carrot weevil · Carrot-willow aphid · Celery fly · Potato rot nematode · Root-knot nematode · Sciarid fly · Silver Y moth · Swift moth|
|Adverse conditions||Drought · Iron deficiency · Magnesium deficiency · Nitrogen deficiency · Nitrogen toxicity · Phosphorous deficiency · Sun scald|
|Diseases||Aspergillus ear and kernel rot · Anthracnose · Bacterial soft rot · Crazy top of corn · Grey leaf spot of corn · Charcoal rot · Corn smut · Corn stunt disease · Fasciation · Fusarium ear and stalk rot · Maize dwarf mosaic virus · Northern corn leaf blight · Pink root of onion · Pythium · Stewart's wilt|
|Pests||Aphid · European corn borer · Cutworm · Leafminer · Root-knot nematode|
|Adverse conditions||Bolting · Calcium deficiency · Phosphorus deficiency|
|Diseases||Aster yellows · Bacterial leaf spot of lettuce · Downey mildew · Grey mould · Lettuce infectious yellows virus · Mosaic virus · Sclerotinia rot|
|Pests||Aphid · Cutworm · Flea beetle · Root-knot nematode · Slug|