RED SPIDER MITES (TETRANYCHUS EVANSI) – AN IMPORTANT PEST OF SUMMER TOMATO CROP
Red spider mites (TETRANYCHUS EVANSI) are pest which can cause major losses at all stages of the crop. These organisms are eight legged non insects and suck the sap being living underneath the leaves.
Tomato [SOLANUM LYCOPERSICUM] crop is one the main vegetable crop among the Indian farmers grown in summer season. The tomato crop is invaded by different kind of insects, pests and diseases.
The fecundity of Red spider mites is so high that their population may go more than 1 lakh within a span of one month at high dry temperatures. In high humid conditions the reproduction rates are lesser.
Red spider mites undergo 5 stages. Egg, larva, protonymph, deutonymph, and adult.
Eggs of the Red spider mites (TETRANYCHUS EVANSI) are round shaped and orange in colour, bright when laid, turns reddish rusty by the time of hatching. If the eggs are unfertilised the get converted to males.
A single female adult can lay more than 100 eggs in 3 weeks’ time..
Young Larvae will be in light green or pinkish coloured, slightly larger than eggs with six legs. The spider mite larvae feed on plant tissues, sucking the sap creating the paler spots on the leaves.
On growing the larval colour changes and spots began to appear.
Once the larvae grows they have to attain the nymphal stage of Red spider mites (TETRANYCHUS EVANSI) looks similar to adults with eight legs but are little smaller the colour will be greenish to orange red.
Initial nymphal stage is Protonymph which is shorter and later nymphal stage is called Deutonymph. During this stage they can form the web.
Female mites are little bigger [0.5 mm] than males [0.30 mm]. Females are broad oval in shape and males are more elongated triangular in shape. Males also differ in colour and will be straw coloured or orange coloured. Adults can reproduce the both sexually and asexually and unfertilised eggs hatch out as males. Adult mites can also form he webs.
The tomato Red spider mites (TETRANYCHUS EVANSI) resemble other common spider mite’s species two spotted mite (Tetranychus urticae) and bean spider mite (T. ludeni).
The mites can be found undersurface of the leaves near the leaf veins. They may also move over to the other side also. Sucking sap or feeding makes the leaves yellowish white and mostly mottled. In severe infestations these red spider mites spin webs, first at under surface, later full leaves, sometimes the whole plants will be densely webbed. In high severe conditions the plants may even die.
Crops of Solanaceae family like Potato, brinjal, weed Solanum nigrum, beans, Citrus plants, cotton, tobacco, roses and other ornamentals.
Movement of Red spider mites from plant to plant:
Red Spider mites are spread through winds, mites can walk shorter distances in search of hosts, contaminated tools, and workers’ clothes and longer distances spread by movement of infested hosts.
- Make the tomato crop grow in clean and healthy environments with proper nutrient management practices and plants grow stronger and may tolerate the attack.
- Check for the alternate hosts are not in the vicinity of the crop at the same time they may be grown trap crop.
- Maintain hygiene and train the workers to avoid the spread on mites from plant to plant.
Miticidal or acaricidal sprays:
The acaricides from naturally available substances are used to clip the mites infestaions. Royal mite 2mL/L + Amruth Almite liquid – 2ML OR Econeem plus - 1 mL/L or of water.
Red spider mites by nature dwells under surface of the leaves and near the veins. Spraying on the surface of the leaves may not kill them, but they can be killed when the miticide/acaricide can reach the down surface, with translaminar activity. Some the miticides/acaricides which may be used to kill the red spider mites are as follows.
Spray with- Maiden-1ml/ltr of water or Kunoichi- 1ml/ltr of water + kranti- 2ml/ltr of water.
Sree latha. B
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