Wireworm - a merciless pest of potatoes
In terms of the total damage caused to the potato plot, the wireworm, perhaps, will yield little to the Colorado potato beetle. But they write and say a lot about the Colorado potato beetle, all the advertisements are full of the names of the most fashionable preparations for the successful fight against the American “robber,” and the handsome beetle on potato tops sits like a big ladybug on the picture, and the leaves it ate immediately rush in the eyes.
But the wireworm is not visible and not heard, nothing is written about it in advertising, and there are practically no accessible and widespread drugs to combat it. At this time, the pest is slowly doing its “dirty” business.
Nutcrackers, wireworms (lat. Elateridae) - a family of beetles. The body length is usually 7-20 (sometimes up to 50) mm. About 10 thousand species in Eurasia and America; in Russia, several hundred species, almost everywhere. Larvae (wireworms) damage the roots of many plants. The name received in connection with the characteristic features of the structure and behavior. Below, on the prothorax, there is a finger-shaped process directed backward, and on the mesothorax, a corresponding notch. The beetle turned on its back bends, removing the process from the recess and resting it on its edge, and then clicks the process back into the recess. As a result of this click, the bug bounces. The beetle will continue to click until it flips to the abdominal surface and stands on its feet.
The nutcracker development cycle is completed in 5 years. In early spring, female beetles, leaving wintering, from May to July (depending on the zone) lay white small eggs in cracks, under lumps of soil, under heaps of weeds and plant debris left in the garden (0, 5 mm). Laying is carried out in small heaps (3 to 5 pieces each). The fertility of one female is approximately 120-150 eggs. After 20-40 days, depending on the zone and type of the nutcracker, larvae hatch from eggs, which grow and develop for 3-4 years. Larvae live in the ground, in the first year they feed on the underground parts of plants, but they do not damage the cultivated ones at this time. In the second year, the larvae increase in size, acquire a yellow or light brown color, and become very mobile. Their body is thin and very solid, for which they are called wireworms. It is almost impossible to crush the wireworm, it is easier to tear. From the second year and later, the wireworm is the most dangerous. In the fourth year, an adult larva pupates in the soil, and in the early spring a new generation of beetles flies out of the pupae.
The damage caused by wireworms is enormous. The wireworms are drilled into root crops and tubers, make moves in them, causing decay and making them unsuitable for storage.
The biology of nutcrackers has been better studied in Palearctic species, less in non-Arctic species, very poorly in tropical species, there are only small fragmentary records about them.
The Russian name for “Nutcrackers” (and the English name for “click beetle”) is given to these beetles due to the sound made during the operation of the hopping mechanism.
Larvae have a separate name - wireworms, because of their elongated body with hard shiny coatings, which are serious polyphagous pests, damaging the underground parts of agricultural, horticultural and forest crops.
How to get rid of wireworm?
To reduce the number of pests in the infield, the following measures are recommended:
- in early spring - deep plowing or digging of the soil, destroying weeds, especially creeping wheat grass;
- place potatoes after peas and beans;
- in the fields heavily populated with wireworms in early spring, 1-2 weeks before planting potatoes, do bait sowing. To do this, sow seeds of oats, barley, corn, wheat of 4-5 grains into nests at a distance of 50-70 cm or with a line. Then dig up the seedlings of these crops together with the wireworms gathered on them and destroy them;
- lay in the soil to a depth of 5-15 cm bait in the form of a piece of tuber, beets, carrots or any meal at the rate of 1-2 pcs. on 1 m², marking these places with twigs. After 3-4 days of bait, remove and destroy the pests accumulated on them;
- to reduce the harmfulness of wireworms in the rows of potatoes, it is recommended to sow salad, the roots of which these pests feed;
- significantly reduces the number of wireworms and the harmfulness of their larvae liming of acidic soils;
- apply granular insecticides before plowing or planting potatoes. You can cook them yourself. To do this, sprinkle 5 kg of granular superphosphate with a thin layer on a plastic film and spray with one of the pesticides (actellik - 15 ml, decis extra - 4 ml, karate - 1 ml) diluted in aqueous acetone solution (80 ml of water + 200 ml of acetone) . Dry the resulting preparation in the shade and sprinkle over the plot (this amount is calculated per 100 m²), then dig it immediately. In another case, when planting potatoes under a shovel, put 5 granules of processed superphosphate in each hole;
- before planting potatoes, water the soil with a solution of potassium permanganate (5 g per 10 l of water) at the rate of 0.5 l per well or under the root. Apply the solution only on alkaline soils. You can also pour potatoes with a three-day infusion of celandine (100 g of chopped plant mass per 10 l of water), nettle (500 g per 10 l of water), dandelion (200 g per 10 l of water), coltsfoot (200 g per 10 l water) and repeat this procedure 2-3 times with an interval of 7 days.
Bait Control Techniques
There is a rather laborious, but quite effective way of catching larvae and beetles on bait. In this case, you will have to check the traps every 2-3 days, but you will be surprised to see how many larvae gather there a week before planting potatoes. In practice, it happened to choose from such traps up to 8-10 larvae. It’s troublesome, but if you remember that each larva will gnaw your potatoes for 3 years, then the game is worth the candle. It is usually advised to stick slices of raw potatoes on sticks and then bury them in the ground, leaving a free end on the outside. After checking the traps and selecting the larvae, the sticks are instilled again, but already in another place of the site. So it is recommended to do it if necessary all summer.
You can also use glass jars in which potatoes, carrots or beets are laid at the bottom. Banks instill a neck in the shady places of the site, pests should also be selected every 2-3 days. Yes, by the way, do not forget to update the slices in pieces or replace the bait altogether, otherwise the larva will decrease its appetite.
Cunning gardeners catch larvae on ordinary fishing line. To do this, pieces of potato are strung on it, the distance between them should be about 10 cm, the bait is buried to a depth of 10-15 cm in the groove. With this method, the catch will be even greater. After 4-5 days, the fishing line is selected, the larvae are scalded with boiling water or burned. By the way, chickens eat wireworm larvae with appetite. If the larvae are offered a choice of potato slices or sprouted seeds of wheat, barley or corn, they will leave the potatoes alone. Before planting potatoes or later - in the aisles - sow the seeds of bait crops. The wireworms gathered on the roots are selected by pulling out the plants. Cereals are advised to sow the entire season - until the garden is freed from the larvae.
It is sometimes advised to treat the seeds of barley, wheat, corn, or other bait crops with the Decis and Karate preparations before sowing. Then you need to dry the seeds in the sun and sow. In this case, part of the larvae will be additionally destroyed by the preparations, because they prefer to feed on seedlings, and at this time the preparations are still active. The validity of these drugs is about a month, and by the time the root crops are harvested, harmful substances are no longer dangerous to humans.
Applying mechanical methods of capture is, of course, very troublesome, but promising. Indeed, several generations of larvae usually live on the site. And they themselves will never leave your landings - there are no miracles. A less time-consuming method is to dig several holes evenly in the area at the very beginning of spring, into which to put large bundles of rotted grass, hay or straw. Wireworm larvae will certainly gather in these pits in search of heat and nutrition. And after a few days, this grass must be selected and burned. The effectiveness will depend on the efforts, because the operation must be repeated repeatedly (according to reviews, a 20 to 90% reduction in the number of pests is achieved).
Experienced gardeners for particularly valuable, varietal plantings of potatoes are advised to apply preplant soaking of tubers in a strong solution of celandine. It is poisonous in itself, but if tubers are grown for seeds, this method can also be used.
Potassium permanganate is good only with a small population of wireworms.
Of these methods of control, the most harmless is watering potassium permanganate before planting. The solution should be pink, consumption - a bucket of 10-15 holes. You can process the planting material of potatoes before planting a stronger solution of potassium permanganate. True, the effectiveness of this method is good only with a small population of soil with wireworms. Experts advise to introduce ammonium-containing fertilizers before sowing root crops and planting potatoes, without fail with planting in the soil, so that the smell of ammonia is preserved. You can add 15 g / m2 of ammonium nitrate, or up to 30 g / m2 of ammonium sulfate. The latter is preferable.
If it was not possible to cope with the problem by agrotechnical, mechanical and other methods, then the use of the drug bazudine remains in reserve. Its active substance diazinon is highly toxic to humans and other warm-blooded. And the standards for making bazudine are quite high - up to 40g / m2, therefore it is reasonable to use this method only with a large number of pests. More harmless ways have not yet been invented.
How do you deal with this pest?