In comfortable greenhouse conditions, it is good not only for heat—loving vegetable crops – their numerous enemies here have much more chances to survive and breed. Pests in the summer and in the open air are not bad, but they feel much better in protected ground, they eat more actively, they populate plants faster. One of these enemies are thrips. We will tell you how dangerous these insects are and what effective means will help to destroy them.
What are the dangers of thrips
Thrips are very small insects that are difficult to notice and even more so to carefully examine with the naked eye. These harmful species have a certain specificity of the body structure and are slightly different from other insects (aphids, whiteflies, etc.).
Thrips on cucumbers
Different types of thrips leave similar damage, but they harm different cultures to different degrees. Cucumbers, for example, are more tender than Solanaceae — external damage from thrips in the former is more pronounced. If on the leaves of nightshade after feeding the larvae there are more often strokes or necrosis of irregular shape, black spots of excrement on top, then on cucumbers such symptoms are observed only at the beginning, and then the leaves quickly dry up. This is how cucumbers Thrips tabaci Lind damage. and his “colleague” Thrips nigropilosus Uzel. Frankliniella occidentalis Perg. it also feeds in the flower buds of cucumbers, as a result of which the flowers are deformed and the fruits grow ugly.
Eggplant thrips
Everyone knows the irritation, redness, itching on the hands (or more serious allergic reactions) that appear after working with eggplant bushes. Most often this happens in greenhouses and greenhouses. The reason for this reaction is the small hairs of the trichome, which are densely covered with eggplant leaves. Breeding selection is aimed at creating varieties and hybrids of eggplant with a minimum number of these hairs. This is done for our convenience. But seven years ago, entomologists began to warn about a very interesting problem that gardeners may soon face.
Here’s the thing. Eggplant is damaged mainly by Thrips tabaci, its larvae prefer group feeding on the underside of the leaf. And it is she who has the eggplant pubescent especially strongly. The hairs-trichomes have a complex structure — under strong magnification, one vertical needle and horizontal needles located on the sides are visible. Adult insects and larvae of thrips, moving along the leaf, fall on these needles, piercing them through.
When we understand this process, it becomes clear why eggplant is damaged by thrips to a lesser extent compared to other crops. Therefore, it is obvious that with the spread of varieties with minimal leaf pubescence, the harmfulness of thrips on eggplants will soon be the same as on other plants.
In addition to Thrips tabaci and Thrips nigripilosus, Thrips palmi Karny can be seen on eggplants.
Thrips on peppers and tomatoes
It’s hard to believe, but 30 years ago, thrips in Europe on peppers were practically not found either in the open or in protected ground. Occasionally, individuals or even populations from neighboring crops could get on pepper, but they, as they say, “did not stay long.” After perestroika, imports flooded into our country — flowers, vegetables and fruits, and with them the frequency of penetration of invasive pest species into the territory increased. In this way Frankliniella occidentalis also penetrated to us.
Frankliniella occidentalis has been recorded on 250 plant species. Pepper fell in love with him as much as tomato. This species is considered especially harmful because, in addition to the main negative effects on damaged plants, it is an active carrier of dangerous viral diseases. On pepper, it also damages the fruits — external manifestations look like small necrosis in area. The marketable value of fruits is falling, but the main thing is that the infection with alternariasis increases significantly. It causes dry rot on the fruits, they become unfit for consumption or sale.
Cucumber mosaic virus is also dangerous for peppers, which causes curly pepper leaves. And this infection is also carried by Frankliniella occidentalis. There are several options for the development of the disease. With a transient form, the plant dries up, while remaining green. With the so-called brown form, during the budding period, individual parts of the leaves turn brown and dry up, the disease spreads through the plant from the bottom up. With a yellow shape, the leaves, respectively, turn yellow, the plant ceases to develop and form fruits. It is not difficult to guess what happens with the dwarf form of the disease.
Over the past couple of years, data have appeared in the scientific literature on the disease of sweet pepper bronziness, the causative agent of which is the tomato bronziness virus, actively spread by Frankliniella occidentalis.
Also on pepper you can now find Thrips tabaci and Thrips palmi Karny. Frankliniella occidentalis is also considered the most dangerous of the several types of thrips that damage it. The virus of bronzing carried by him on tomato has been manifesting itself for a long time and “in all its glory”. Moreover, if the disease is quite rare in capital, large greenhouses, then in film greenhouses and greenhouses it occurs every year. Previously, he was complained about in the southern regions of the country. Over the past 8 years, tomato bronze has actively spread across the middle belt and more northern regions.
The symptoms of this disease are very diverse, in some cases it can be confused with other viral or even fungal diseases. Sometimes the picture becomes characteristic, it was she who gave the second name of the disease — spotted tomato wilt. Due to wilting and loss of presentation, you can completely lose the harvest.
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