Other
Broad Mite
Polyphagotarsonemus latus
Mite
In a Nutshell
- Deformation and discoloration of leaves, leaf buds, flower buds and fruits.
- Thick brown areas under the leaves.
- Stunted growth.
- Die back of shoots may occur.
Other
Symptoms
The damage often resembles the damage caused by the misuse of herbicides and nutrient deficiency. Leaves curl, thicken and become brownish. Corky brown areas appear between the main veins on the underside. Blooms abort and young foliage is often deformed. Stunted growth and die back of shoots can be observed when population density is high. Feeding damage of the mites causes silvering of the fruits and the appearance of corky brown areas.
Recommendations
Organic Control
Use natural predators of the broad mite such as Neoseiulus cucumeris and Amblyseius montdorensis to control the disease after an infestation. Also, try Garlic spray and insecticidal soaps. Hot water treatments of young plantlets (43°C to 49°C for 15 minutes) also help to control the mite infestation.
Chemical Control
Always consider an integrated approach with preventive measures together with biological treatments if available. Use chemicals only in case of high pest pressure. Mite pests are hard to control using chemical treatments due to the mite’s short life cycle that makes them likely to develop resistance. If miticides are really necessary, spray products containing abamectin, spiromesifen or pyridine.
What caused it?
Broad mites pierce young leaves and buds and suck up the sap that oozes from the wound. Their saliva contains plant-hormone-like substances that cause tissue deformations. The mites are very small and difficult to see without a hand lens. The adults are about 0.2 mm long and oval-shaped. The color varies between yellow and green. The adult females lay about five eggs per day either on the underside of leaves or in the depressions of fruits. The larvae hatch in two or three days. The spread of mites is very slow unless they use an insect as a vector or are spread by wind. This species thrives in warm humid conditions, e.g. in greenhouses.
Preventive Measures
- Avoid planting downwind next to infected crops.
- Avoid planting healthy crops next to infested fields.
- Remove plants with symptoms and adjacent plants to avoid spreading.
- Support natural predators by reducing the excessive use of pesticides.
- Be sure to provide plants with ant repelling traps.
- Remove and destroy plant residues after harvest, and wait for at least one week before planting other crops.
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