Environmental Entomology (1986) 15, 594-600

Roger R. Youngman and Martin M. Barnes (1986)
Interaction of spider mites (Acari: Tetranychidae) and water stress on gas-exchange rates and water potential of almond leaves
Environmental Entomology 15 (3), 594-600
Abstract: Preparation of almond orchards for harvest by withdrawal of irrigation may result in prolonged periods of water stress. It is during these periods (from July to mid-August) that mite populations often increase and are associated with partial defoliation. The impact of spider mites and water stress, alone and in combination, was investigated on gas exchange and water potential of almond leaves during the 1982 and 1983 growing seasons. The impact of water stress on mite densities was also studied in 1982. In both years, water stress caused highly significant reductions in leaf water potential, whereas mites alone had no measurable impact. In 1982, significantly higher mite eggs and motile stages developed on water-stressed foliage as compared with unstressed foliage. The effect of mites on gas exchange of water-stressed leaves was greater than on unstressed leaves in 1982 as indicated by significant interactions. Significant interactions representing the same trend did not occur in the 1983 trial. When water stress was severe, as in 1983, no additional impact of mites on gas exchange was detected.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)

Research topic(s) for pests/diseases/weeds:
damage/losses/economics
environment - cropping system/rotation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Tetranychus urticae	Almond (Prunus dulcis)	U.S.A. (SW)
	Tetranychus pacificus	Almond (Prunus dulcis)	U.S.A. (SW)
	Tetranychus turkestani	Almond (Prunus dulcis)	U.S.A. (SW)