The first symptomsthe diseaseusually appear at the end of May, and in less favorable weather conditions they appear later.Initially watery at the edges of the leaves , yellowish-brown, then brownish, misshapen, gradually enlarging patches.
You can observe brown, slightly convex spots on the fruit, clearly harder than the he althy part of the fruit.The boundaries of the stains are not sharp.The browning extends deep into the flesh and may even cover the whole fruit in the next few days.
Conditions favoring the development of plague
Favorable weather for the development of late blight means frequent and abundant rainfall, high air humidity, temperature around 15-18 ° C and long-lasting wetting of the leaves.In conditions of high air humidity on the underside of the leaves, on the border of he althy and infected tissue, you can see a delicate white coating.
In protecting tomatoes against blight, it is recommended to carefully harvest and destroy infected plants. They must not be overfertilized with nitrogen, as this is conducive to their infestation. Chemical treatments are the primary method of protecting tomatoes against potato blight.
The first spraying should be done just before the appearance of favorable conditions for infection or at the latest when the first symptoms of disease appear on the plants. The best method of combating is to use systemic fungicides as the first one, while for subsequent treatments, performed every 10-14 days, use surface-active agents.
You should also remember not to use the same preparations for chemical treatments, because it favors the formation of resistant forms.Dry top rot is often mistaken for tomato blight on tomatoes.Concave spots appear on the tops of the fruit (hence the name of the disease), which darken over time, wrinkle and dry up, very often covering most of the fruit. A brown stain extends deeper into the fruit.
Dangerous shortage of lime
In conditions of high humidity, fruits with symptoms of dry top rot are infested with bacteria and fungi, and as a result they rot. The immediate cause of the disease is calcium deficiency in fruit buds during their intensive growth.Calcium deficiency in fruit tissues may result from low content of this nutrient in the soil, disturbances in uptake and transport of calcium in the plant, or damage to the roots.
The occurrence of this disease is favored by excess nitrogen, magnesium and potassium in the soil, and fluctuations in humidity and ambient temperature. Also, excessive watering reduces respiration and root activity, which interferes with the uptake and transport of calcium to the fruit being formed.
In case of disease symptoms, spray the fruit with a solution of fertilizers containing calcium, e.g. calcium nitrate. We perform treatments when the fruit is larger than the walnut, on cloudy days (to avoid sunburn). We repeat them 4-5 times every week.Also avoid wetting the tops of the plants. Some parts of the leaves may be damaged, but this is no longer dangerous for the plant if most of the fruit is already set.
Tomato alternaria
Another disease that affects fruit and other plant organs is tomato alternaria, caused by the fungus Alternaria porri.Dark spots appear on the leaves, and on their surface there are concentrically arranged zones resembling wood rings.Symptoms may also appear on fruits in the form of black spots with velvety spores.
The fungus hibernates on infected plant debris, and the best method of preventing this disease is to stop growing tomatoes for at least several years.We do not use the same preparations for chemical treatments, because it favors the formation of resistant forms.
