Also known as fruit tree red spider mite. Red mites overwinter as brick-red, 0.16 mm long winter eggs that are usually deposited around the buds and in rough bark on old wood.
European red mite [Panonychus ulmi]
Heavy winter egg infestation can be identified by fingers becoming red during pruning. The larvae hatch during the 1st to 3rd leaf stages (Picture 1). Summer eggs are deposited preferentially on the bottom surfaces of leaves. There are 2-3 generations per year in cool regions and up to 8 in warmer climates., Infesting the entire canopy. In late summer, the females move to the nodes and to old wood to deposit their winter eggs.
Fruit tree red spider mite
Found in many crops but particularly in pome and stone fruit and grape vines.
Pattern of damage
The red spider mite's sucking activity leads to dark leaf tips, puncture-spots, upwardly arched leaves and thin, short shoots (Picture 2). Infected leaves have reduced photosynthesis resulting in insufficient ripening of fruitand resulting quality losses. In late summer, infestation is recognizable by the rust-brown discoloration of the canopy. The wood has often not sufficiently matured, which increases the vulnerability of shoots to winter frost.
Chemical control is urgently required in the case of red fingers during vine pruning and/or infestation of 20 winter eggs per node in spring. Use a hand lens to look for eggs and larvae. After flowering, the shoot surfaces must be checked for red spider mite infestation before symptoms appear on the leaves. Economic thresholds to justify spraying insecticides vary according to plant growth stage, it is also worth determining whether there are beneficial insects present that might control the mite infestation. After flowering, an infestation of 70% of inspected leaves is considered critical. Prior to fruit formation emergence, 50% is considered critical. Prior to the last spraying, an infestation of 30% of the leaves is cause to conduct control measures.