Usually ferrous sulfate poisoning occurs on old leaves, with the symptoms of leaves spots, growth atrophy and flowering delay.
The causes of tomatoes ferrous poisoning:
1. According to experts’ investigation, excessive ferrous in soil not the only reason to cause tomatoes poisoning, however, there also another important reason is low PH value in soil that makes tomatoes ferrous absorption ability enhanced and absorpted ferrous gathered in leaves.
2. Zinc deficiency symptom also can cause ferrous poisoning because zinc deficiency can lead tomatoes to absorb more ferrous.
Prevention and treatment:
1. Balance law between ferrous and manganese
The two mineral elements--ferrous and manganese are opposed to each other, which means one element can inhibit the absorption of another element. Therefore, when tomatoes ferrous poisoning appears, we can apply some manganese fertilizer to inhibit ferrous absorption like manganese sulfate.
2. Ferrous poisoning also can be treated through the use of zinc fertilizers such as zinc sulfate or adjustment on soil pH value.