Index
1- What is the yellow vine spider?
The yellow spider is a polyphagous mite of the tetranychid family.
At present, the yellow spider has been detected in almost all the Spanish wine-growing regions , with the exception of the Galician ones, but it is in the southern half where it causes the greatest damage.
2- Damages caused by the yellow spider.
The damage caused by this can be significant, since it is not limited to the death of the attacked foliar tissues, but, in our climatic conditions, it can result in heavy defoliation.
If the attack of the yellow spider is strong and causes defoliation before the second half of September, the spiders, which have not yet finished their cycle, seek new foraging places in any green part of the same strain or of its neighbors (branches , scraps, berries).
3- States of development.
Regarding the stages of development , when they are adults the female is oval in shape and presents differences depending on whether it is in active or wintering form in diapause.
The active spider is about 0.5 mm long and greenish-yellow with two darker lateral spots.
The wintering in diapause is somewhat smaller, orange to brick red in color and does not have the two dark spots.
The male is somewhat smaller than the female and has a more pointed abdomen. They both have 4 pairs of legs.
The egg is spherical and measures little more than 0.1 mm; freshly applied, it is translucent and immediately becomes opaque and amber-yellow in color.
4- Biological cycle of the spider. Climatic factors.
High temperatures shorten the mite’s cycle, thereby contributing to its rapid multiplication.
At an average temperature of 25ºC, a generation takes place in 10 days.
The lower threshold of development is around 10-12ºC for both eggs and later stages , the optimum for development at 30-32ºC and the maximum above 40ºC.
Regarding relative humidity, it is more favorable when it is low, with an optimum between 30-50%.
Known natural enemies are some insects such as Coccinellids, Chrysopids, Anthocorids and mites of different families.
5- Symptoms of the plague attack.
The initial symptoms produced by the attack of this mite on the leaves , consists of yellowish green areas with necrotic pits, which are more easily seen against the light, placing the leaves against the sun.
Heavily attacked leaves age quickly and fall off.
In the case of high populations, they can also attack the remaining green organs: branches, berries and scraps, in which necrotic pits also appear.
In the berries, the symptoms can be confused with those of powdery mildew , being differentiated by the presence of the whitish molts of the mites and by not continuing in the contact zone of two berries.
6- Means of fight and protection strategy.
The protection strategy against this mite begins with the elimination of the weeds in their entirety by means of labors or herbicides, and especially those closest to the trunks.
Regarding chemical protection , a specific miticide must be chosen .
The treatment has to place the pesticide on the underside of the leaves and in the recommended amount, otherwise the miticide may be imputed ineffectiveness.
Other articles related to pests and diseases of the vine are:
- Vine tinder. Definition, symptoms, damage and control.
- Downy of the vine. Characteristics, damage and control.
- Powdery mildew of the vine in vineyard. Symptoms, damage and control of the disease.
- Botrytis of the grape. Definition, symptoms and recommendations for control.
- Green mosquito on the vine. Description, characteristics and treatment of the pest.
