Fighting Cruciferous Fleas In The Garden

2024 Author: Sebastian Paterson | [email protected]. Last modified: 2023-12-16 13:47

The beetle is small, but the harm is big

Delicate leaves of early shoots of vegetable crops (lettuce, radish, spinach, radish) and seedlings of cruciferous plants (cabbage, beet, swede), characterized by a short growing season, are attacked by small bugs from the very first hours after planting in open ground, on which many beginners gardeners don't even pay serious attention.

Already after a day or two, it turns out that the leaves of young plants are so badly damaged by these insects - cruciferous flea beetles, that there is even a question of replacing seedlings. These pests are widespread in our country (except for the Far North), they cause significant harm in the north of the European part, in non-chernozem and central regions, therefore they are considered one of the most dangerous pests of cruciferous crops.

These small (2-3 mm in size) dark beetles jump high enough like fleas, which is why they began to be called "cruciferous fleas", although according to their taxonomy they belong to the genus Phyllotreta (the leaf beetle family). In the non-chernozem zone, cruciferous crops are mainly affected by six species of flea beetles, although, according to some experts, about 80% of the total number of these fleas in the middle, northern and western regions of the country is wavy (Ph.undulata Kutsch). A wavy flea (2-2.8 mm in size) is black, with a yellow stripe on each elytra with a deep notch on the outside.

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As soon as the snow melts, after leaving the wintering, which the beetles spend in secluded places of the personal plot, most often under plant residues and fallen leaves, in the surface layer of the soil of the garden, in the crevices of greenhouses and greenhouses, on forest edges, they feed on cruciferous weeds (rape, shepherd's bag, field rape, wild radish, jaundice, field jelly). In the middle zone of the country, this period usually falls on the end of April - beginning of May.

With the emergence of cultivated plants, beetles fly over to their foliage, from which they scrape off the top layer and gnaw out depressions along the edges of the leaves, as a result of which, with significant damage, the leaves dry out. On the more tender leaves of turnip and radish, they gnaw through holes (1.5-2 mm in diameter). If the growth point is damaged, seedlings can easily die.

These beetles are most active during the sunny hours of the day (periods from 10 am to 1 pm and from 4 pm to 6 pm), when dew drops dry on the leaves. Insects are especially voracious in dry, hot weather and are able to destroy completely young seedlings of cruciferous crops in a matter of days (sometimes even before the cotyledons appear above the soil surface). This is due to the increased biological activity of flea beetles at high temperatures (20 ° C and above) and inhibited development of plants during drought, which is why they do not have time to "escape" from damage.

With mass reproduction, cruciferous fleas quickly destroy cabbage seedlings, especially the first 10 days, while it has not yet taken root after planting in open ground. Damage to beetles is also dangerous for young shoots of radish and radish in the phase of cotyledons and the first true leaves. In some cases, cruciferous fleas also attack the hardened testes of cruciferous plants, eating small (1.5-2 mm in diameter) pits on the buds, pods and leaves and significantly reducing their yield. In cool and humid weather, their activity decreases.

In summer, fleas sometimes severely damage summer radish crops, as well as cauliflower seedlings. Of the flowering plants most affected by this pest, Levkoi and Alyssum are most often called.

Females lay small, yellowish eggs in the soil. For example, in the conditions of the Moscow region, the wavy flea lays eggs from the second half of June to the end of July. Eggs (0.3-0.4 mm) are light yellow, translucent, oblong-oval. In worm-like larvae hatching 4-10 days after laying eggs (depending on weather conditions), the body is thin, long, light yellow with three pairs of pectoral legs. The hatched larvae in the soil feed on small roots for 2-4 weeks or eat root crops at the root collar. After 8-12 days, new beetles emerge. Larvae pupate in the soil. A new generation of young beetles also feeds on cruciferous crops, and with the onset of cold weather goes to winter. During the year, all cruciferous flea species develop in one generation.

Control measures against cruciferous flea beetles should consist of a complex of agricultural practices and methods of biological and chemical protection. In late autumn, you should carry out a deep digging of the soil in the beds where you grew cruciferous crops in order to turn the beetles ready to winter on the soil surface - then they will die with the first cold weather.

To prevent the mass appearance of fleas, it is recommended in early spring to timely destroy weeds (especially from the cruciferous family), growing both on the site and on the periphery of the sites, on the roadsides: fleas feed and breed on it. Early planting of seedlings of cruciferous crops should be adjusted for cloudy weather, when the beetles are not particularly active (sowing seeds as early as possible through greenhouses and hotbeds). On the other hand, the sowing of turnips and turnips in the middle and northern lane can be carried out at a later date - in June, when the number of flea beetles begins to decline.

In hot weather, nurseries and seedlings planted in open ground are shaded, for example, with large leaves of burdocks. It is very important to ensure the implementation of agrotechnical methods that accelerate the growth and development of young plants: feeding with slurry, saltpeter or other nitrogen fertilizers, regular watering and loosening. There is evidence that spraying foliage with slurry and a solution of bird droppings has a negative effect on flea beetles. More developed and strong plants are characterized by greater resistance to pest damage.

The leaf surface of newly emerged seedlings and small cruciferous seedlings is sprinkled with ash or a mixture of it with tobacco dust (1: 1). This procedure only temporarily scares off flea beetles from the plants, so it is repeated several times (usually immediately after watering the plants).

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In household plots, cruciferous flea beetles can be fought by catching them on plywood shields, smeared on top with sticky substances - special long-term non-drying glue, resin or tar. The underside of the shield in contact with the plants is not lubricated.

With a high number of pests, unfavorable conditions for young plants or for large-leaved seedlings, it is still more advisable to spray with one of the insecticides. As an effective insecticide in the practice of home gardens, the trading network offers (based on 10 liters of water): fufanon, kemifos, Iskra M, actellik. Consumption of working solution 1 l / 10m². Planting is processed in the evening, when fleas sit quietly on the plants, but no later than 20 days before harvesting.

Since some garden crops - lettuce, radish, celery, parsley, begin to be eaten at the beginning of summer, you still should not treat these plantings with pesticides, it is better to spray the plants with ash infusion or decoction of tomato plants. In the evening, a glass of ash is poured with 9 liters of water, stirred, allowed to settle until morning, after which all the liquid above the sediment is drained and, if necessary, filtered.

Or such a composition: 2 kg of the remains of fresh tomato plants or 0.5 kg of its dry mass are poured with 5 liters of water, infused (3-4 hours), then boiled over low heat (green mass - 30 minutes, dry - 2-3 hours); filter, dilute with water (1: 2) and add soap (20 g per 5 l of solution). And the plants are treated against cruciferous fleas.