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Video: Scoops - Pests Of Potatoes
2023 Author: Sebastian Paterson | [email protected]. Last modified: 2023-11-26 20:34
How to recognize dangerous scoop potato pests and how to deal with them
In the family of scoops, there are many pests of agricultural crops. The scoop is often referred to as "myotis" as they are nocturnal. They fly out of their hiding places with the first twilight, so during the day you will not find them fluttering over the beds. And in daylight they hide in cracks in the bark, between the boards of the house and outbuildings, in the grass, merge (due to their color), huddling, with the trunk of trees.
As a rule, two groups of scoops may appear on potatoes: the underground species - the gnawing (winter) scoop (Agrotis segetis) and the aboveground ones - the potato (marsh or purple) (Hydraecia micacea) and the medullary (common) (Gortyna flavago).
In recent decades, outbreaks of foci of winter (gnawing) moths have been noted in the regions of the country and in the Leningrad region. It is a polyphagous pest that feeds on potatoes, carrots, onions and other crops. Its single specimens were always present in our plots, but earlier it did not show high harmfulness, it was found and developed on the tracts of row crops. With the reduction of the production area of these crops in agricultural farms, the scoop moved to the plots to us, gardeners. In addition, the hot, dry weather, which was noted in recent seasons and not very severe winters, also influenced its active reproduction.
The imago of the winter moth is a butterfly with a wingspan of 35-50 mm. Her forewings are yellowish or brownish gray. Butterflies lay their eggs on herbaceous plants. It is known that the caterpillars of the winter moth are equally eager to feed on 150 species of plants. Caterpillars have 8 pairs of legs. At the first age, their color is light, in older ages (they reach a length of 50-52 mm) - matte or glossy.
In vegetative potato plants, the caterpillars gnaw the stems at the soil level and somewhat lower, as a result of which they quickly wither and fall. The first instar caterpillar, as a rule, does not damage the tuber skin. Usually, it only makes an inconspicuous hole and a passage, at the end of which it forms a small cavity (chamber), which gradually increases in size and is filled with excrement. Having finished feeding, the caterpillar leaves the tuber, making a new and wider move. As a result of damage, such tubers often rot from secondary infection, and their marketability decreases. Caterpillars of the last (6th) instar hibernate in the soil, where they pupate in the spring.
In the conditions of our North-West, the pest has one generation. In my opinion, the spread and active harmfulness of this pest in summer cottages may have been facilitated by the use of winter rye as a "cleansing" crop, on the shoots and seeds of which older caterpillars "feed" in early autumn or spring.
Caterpillars of potato and common pith scoop develop in potato stalks. They are common practically throughout the entire territory of our country wherever this crop is grown, but the most tangible harm is done by foci - in low or humid areas.
Caterpillars of the potato worm are most harmful in rainy years with moderate temperatures, while damaged stems can account for up to 20-30% of their total number. In potatoes, the caterpillars gnaw a hole just above the root collar, make a move inside the stem, heading up. Having reached the thin part, they go down and penetrate into the adjacent stem. Damaged stems wither and dry out in dry weather, and rot in wet weather. In dry weather, such stems wither and dry up or break in places damaged by caterpillars. After rains or in wet weather, often damaged stems become slimy, their tissue becomes dirty green in color.
Even 20-25 years ago, even a number of potato-growers had doubts and concerns: were these bushes affected by slimy brown bacteriosis, which was then a quarantine object. Cutting these stems lengthwise and demonstrating the presence of semi-dry "crumbs" (ie, pest excrement) in them, we had to convince in this way that the cause of such withering and decay of potato stems is the caterpillar moth plus the aftereffect of secondary bacterial infection of saprophytic (non-pathogenic) microflora. During this growing season, caterpillar plants in the stems, of course, could no longer be found, since they descended into the zone of the root system.
In addition to potatoes, these scoops damage rhubarb, tomato, raspberry, strawberry, sorrel, beetroot, turnip, cucumber, cabbage, hops, gladiolus, dahlia, iris, legumes (more than 50 species from 20 families). They are especially harmful in the European part of Russia and in Western Siberia.
They also develop on wild plants. The butterflies of the potato scoop themselves are quite large, in a wingspan their size reaches 28-40 mm (females are usually somewhat larger than males). The forewings are grayish yellow, dark or brownish gray with a reddish tint, transverse lines and spots, the hind wings are grayish or pinkish yellow with a dark stripe in the apical third of the wing.
Years of potato scoop butterflies in the North-West of Russia are observed from mid-July to mid-October (the most intense in 2-3 decades of August and 1 decade of September). Females lay yellowish-white eggs on perennial cereal grasses (mainly on creeping wheatgrass, less often on foxtail, fescue, timothy, hedgehog, etc.) behind the leaf sheath in groups (usually 20-60 pieces) in 1-3 rows. They are tightly glued together, as well as with the leaf and stem. Only one female lays from 250 to 450 eggs. The eggs then hibernate.
The caterpillars emerge from them in the first half of May. They are of six ages. They feed for a short period on cultivated and wild-growing grasses and grasses, then in their stems (at the same time often damaging their rhizomes) and at 2-3 ages pass into thick-stemmed plants, in search of which they are able to crawl several tens of meters. One caterpillar can damage up to 3 stems, and if nutrition is deteriorating (for example, when there is a shortage of feed), it can switch to other plants. They especially damage potatoes.
In rhubarb, leaf petioles are severely damaged. On strawberries, in addition to flower shoots and leaf petioles, moth caterpillars sometimes gnaw out ovaries and ripening berries, and one caterpillar can damage several plants. The damaged parts of the plant wither and dry out or break off.
The number of caterpillars is gradually increasing due to their resettlement from wild vegetation. The length of the caterpillar is 40-45 mm, their color is from light yellow to fleshy red, there is a reddish stripe along the back, the head is red-brown. Caterpillars have dark brown, wart-like spots with bristles on each body segment. Caterpillars pupate in the soil near damaged plants, starting from the first days of July to the beginning of August at a depth of 5-15 cm. The pupa is yellow-brown, 17-25 mm long, develops in 15-30 days.
The wingspan of butterflies of the common heartworm is 33-42 mm, the main color of the front wings is golden yellow, the hind ones are yellowish white. Forewing spots with a brown border, transverse stripes with a wide violet-brown border. The length of adult caterpillars is 40-45 mm, the color is off-white or yellow, sometimes with a red bloom. The biology of the heartworm is generally very similar to the previous species. The caterpillar of the heartworm pupates inside the stems, below the hole prepared for the emergence of the butterfly. Pupa is dark chestnut, 2.5 cm long. Years of common scoop moths usually begin closer to mid-August and continue until October. Both in-stem species give one generation each.
It is quite difficult to deal with scoops, since these small butterflies lead a hidden lifestyle during the day and fly out of their hiding places only late in the evening. It is noted that the introduction of mineral fertilizers under potatoes leads to a decrease in the number of pests. Frequent loosening of the soil in the aisles during the growing season destroys caterpillar shelters. Spraying with chemical means of plantings on personal plots against these pests, in my opinion, is unjustified, since it is difficult to "grab" butterflies during the summer (in the evening or at night) in this way, almost impossible, and it is unreasonable to treat plants prophylactically. It will be harmful to your health.
You can try to introduce granular bazudin into the furrows when planting tubers to combat caterpillars (consumption 15-20 kg per hectare. But to obtain a high effect, it must be applied to wet soil, and such a moment is not always possible to guess. And economically, in my opinion, this is disadvantageous, although this drug can also scare away wireworms, click beetle larvae.
The most interesting and safe for the health of owners of backyard plots is the catch of "myotis" for fragrant solutions like fermenting molasses during their massive summer. For this, molasses, diluted three times with water, is poured into shallow containers, for example, on a baking sheet, in cans or the bottom sections of plastic bottles, and a small amount of yeast is added. The smell of fermenting molasses attracts butterflies, and, getting into the liquid, they drown in it. In addition, feeding on molasses causes infertility in butterflies. The containers are installed or suspended at a height of 1-2 m in the bushes of currants, gooseberries or other plants. In the morning, butterflies are caught and destroyed.
Usually, the so-called "signal" container is first installed, and when butterflies are found in it, the number of containers is increased. Fermented jam, beer or beer wort are also used instead of molasses. Sweetened water "works" weaker. By the way, in addition to these types of butterflies, a huge number of other pests can also get into the placed containers.
It should be noted that there are also many beneficial insects that reduce the number of moths in our areas. Of these, the most famous are ground beetles, tahini flies, and poachers. For example, in the Leningrad Region, in some years, from a quarter to a third of caterpillars infected with braconids are noted. Therefore, each gardener should grow odorous umbellates (for example, dill) or other plants - nectar plants, which attract these beneficial insects to their backyards with their smell.
It is also important to carry out a serious fight against weeds, especially with cereals, wheatgrass. Against wintering in the soil forms of scoops (pupae, caterpillars), nemabakt can be used. In autumn, it is better to dig the soil on the site at a later date - preferably before the first frosts, in order to raise these forms to the surface. After that, the caterpillars do not have time to go back to a sufficient depth of the soil and freeze out.
Alexander Lazarev, Candidate of Biological Sciences, Senior Researcher, All-Russian Research Institute of Plant Protection, Pushkin
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