|Why do my tomato plants get yellowing and small leaves?
I grow Celebrity, Roma and Better Boy; all seem to curl and yellow at the tops. I fertilize and treat with iron.
|There are quite a few things that can cause the symptoms you describe. The two that come to mind are nitrogen deficiency and fusarium wilt.
Fusarium wilt symptoms are wilting leaves, yellow leaves, slowed/stunted growth, reduced/absent fruit production. This disease is caused by a fungus that lives in the soil. There are no real ways to "cure" this disease. Your best defense is a good offense. Try purchasing tomato varieties that are resistant to fusarium wilt such as Burpee's 'Early Pick' and 'Husky Gold'.
A nitrogen deficiency is expressed as small, pale yellow leaves that may die and drop, and slowed growth. Fruit is small and may be distorted and discolored. The solution is fertilizing. You mention you are fertilizing...how much? Tomatoes are heavy feeders and need fertilizing as follows: At planting time apply fertilizer such as 8-10-8 according to package instructions, sidedress with the same every 3-4 weeks thereafter. It is also very beneficial to work organic material such as compost, leaf mould, or composted cow manure into the soil. You might want to have a soil test done. If your pH is very low or very high, it can interfere with nutrient uptake. I would stop applying the iron if I wereyou, it probably isn't the problem. Good Luck!