1- What is the red spider?
The spider mite known in many ways (red mite, spider mite, yellow spider, etc.) belongs to the class Arachnida, but it is not a spider itself.
It is a highly polyphagous mite scientifically known as Tetranychus urticae that feeds on the plant, specifically absorbing the liquid from the cells, and causing chlorotic spots on the upper part of the leaves.
It is the most abundant and widely distributed species in our country.
The “red spider” has been detected in vineyards of Valencia, Alicante, Almería, Murcia, Navarra and La Rioja.
It attacks numerous trees and shrubs, among which fruit trees are preferably found, including the vineyard.
2- Development stages of the red spider.
Regarding the stages of development , when they are adults they have 4 pairs of legs.
The female is oval and dark red in color, with hairs emerging from whitish bumps; measures about 0.5 mm.
The male is slightly longer, paler and smaller.
The spider’s eggs resemble an onion; they are globose, depressed at the poles, with longitudinal striations and a hair at the upper end.
Spiders overwinter as eggs, deposited around the buds and leaf scars, at the base of the thumbs, and even on the arms and trunk.
The revival of these eggs begins in phenological stage 2 (swollen yolk), reaches the maximum in phenological stage 5 (expanded leaves) and ends in stage 7 (separate influences).
Before finishing the revival , the first females lay the first summer eggs on the leaves.
The laying of eggs of the spider mite is oscillating according to the climate , between 20 and 50 eggs / female.
At the beginning of September the winter egg laying begins in the places indicated above, which lasts until November.
During the rest of spring , all summer and part of autumn, it lives on the leaves, which colonize from the base to the tip of the branch, and 7 to 9 generations follow each other in our Mediterranean climate, with no separation between none of them.
High temperatures and low relative humidity favor their development , shortening the cycle and increasing fertility.
3- Symptoms of the plague.
The symptoms on leaves are spread throughout the limbo in which they appear necrotic pits surrounded by a discoloration.
The first attacks can cause serious damage, such as growth reduction, leaf drop from the base and drying of shoots.
The summer attacks are loss of chlorophyll and defoliation, they mainly lead to a decrease in the level of sugar in the must.
A severe attack can also affect the vegetation of the following year, due to a bad withering of the shoots and a poor feeding of the buds.
4- Control of the plague.
To eliminate this plague, the essential treatments must be carried out , choosing products based on their side effects, not increasing the fertility of the female.
These products to be used must have an acaricidal action.
Recommendations for better control of the pest.
- Do not abuse nitrogenous fertilizers.
- Burn the pruning wood , as there is a winter egg laying there.
The most important treatment to prevent early damage from the spider mite is at the time of sprouting.
Treat with ovicidal products in phenological stage 1 (Winter Stop).