The Colorado potato beetle : how to fight without pesticides ?

The Colorado beetle is a beetle which can, in the event of an invasion, reduce the yield of the potato crop by at least half. But that’s not to mention that once well established in the vegetable garden, it also attacks pepper, tomato or even eggplant plants. It is therefore essential to react as quickly as possible to fight against the Colorado potato beetle, but the best solution is of course to opt for a alternative to pesticides. Let’s take stock of the little tricks and prophylactic measures significantly reducing the population of this beetle.

Doryphore: the return of a sworn enemy of the gardener

After a few years of near-silence, the beetle (Leptinotarsa decemlineata) is resurfacing in our fields and gardens, and more particularly in the regions north of the Loire. Specialists believe that global warming could explain the return of the beetle.

This beetle of the family of Chrysomelidae is a voracious but also a tough one. Its lifespan is approx. 2 ans, which is more than enough to ruin many cultures. Recognizable in adulthood by its yellow livery with black stripes, the Colorado potato beetle is most prevalent from mid-April to the end of June. It reproduces at high speed since a single female can lay nearly a thousand eggs on the underside of potato leaves (among others).

We can recognize the Colorado potato beetle larvae quite easily. They are colored orange and have small black dots. They are great leaf eaters. In less than 15 days, they undergo three successive moults. It is then that they leave the leaves to embed themselves in the ground and do not come out until July, completely metamorphosed since they have acquired their adult appearance.

It’s important to show up very watchful because an infestation of beetles leads to the defoliation total planting of potatoes and other garden vegetables. But the leaves being essential to each plant, the harvest is extremely jeopardized.

Natural fight against the Colorado potato beetle: tips and prophylactic measures to adopt

The gardener has several environmentally friendly solutions so as not to see his potatoes and certain other plants suffer the onslaught of the beetle.

  • Spray some Bordeaux mixture in the garden because it constitutes a repellent effective against the beetle provided that the spraying is carried out two to three evenings in a row,
  • From April, inspect as regularly as possible leaves potatoes.
  • Manually kill adult beetles without exception, as soon as they appear,
  • Crush all the eggs of the beetles as soon as they are laid in order to avoid a new risk of infestation,
  • Opt for a early planting so that the foliage of the potato plants is already adult, and therefore less tender, when the beetles begin to infest the crops,
  • Eliminate systematically regrowth which promote the concentration of these undesirables,
  • Prevent Colorado potato beetle larvae from infiltrating the soil leaving during summer the earth harden sufficiently, which implies not digging or hoeing,
  • Definitely get rid of plant debris and waste from the vegetable garden because they serve as food for the beetles which can therefore concentrate there in large numbers,
  • Perform the potato crop rotation : once every three or four years is enough. This helps eradicate specimens that overwinter in the ground.

Do not hesitate to use the good combinations of plants in the vegetable garden, as some are effective against beetles. This is the case of annual flax with blue flowers and of theail that can be sown or planted in the rows of potatoes or every other row. For a more severe fight, it is possible to plant castor bean et you datura but be careful because these are plants whose toxicity is formidable. We are therefore content to install them at the edge of the space reserved for growing potatoes and not in the rows, and it is absolutely necessary forbid children to touch it. Colorado potato beetles are attracted to these two plants. The females lay there without problems but the larvae are then very quickly poisoned.

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