ISHS Acta Horticulturae 367: VI International Symposium on Pear Growing
THE EFFECT OF TWOSPOTTED SPIDER MITE ON BARTLETT PEAR AND THE MANAGEMENT OF INFESTATION USING DAMAGE THRESHOLDS |
| Authors: | S.C. McNab, P.H. Jerie, D.G. Williams |
| Keywords: | Tetranychus urticae, pear, thresholds, fruit set, water stress |
| Abstract:
A recently completed five year research program studied the effect of twospotted spider mite (TSM) on Bartlett pear and established a set of practical damage thresholds that utilise improved monitoring techniques. Water stress in under irrigated orchards increased leaf scorch at a given TSM pressure. However TSM did not affect leaf water relations prior to leaf scorch. Sensation (Red Bartlett) leaves did not scorch and are highly tolerant to TSM infestation. Leaf scorch damage reduced fruit yield in the following season through a reduction in fruit set. Leaf scorch development was related to various indices of mite infestation including, current level of infestation and a cumulative index that incorporates both the level and duration of infestation. The strongest relationship was observed between the cumulative index and the development of leaf scorch damage. Damage thresholds were established from this relationship and were field tested for two seasons. A simple computer program was written to assist in the collation, calculation and interpretation of the monitoring data. Field testing, conducted by commercial scouts in district orchards, demonstrated that the predictive model correctly determined leaf scorch damage that developed on the 30 blocks monitored. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
