CONSIDERATIONS FOR SIDER WHITE CONTROL ON STRAWBERRIES


 S. L. Poe
 Associate Professor (Entomologist)


 Adequate control of spider mite populations on Florida grown strawberries
achieved in an acceptable and practical manner must be achieved through application
of principles based on knowledge of several determinant factors. These factors
are outlined in this paper and the knowledge necessary for better understanding
each is summarized as what the farmer, pest control operator or management specia-
list should know to control spidermites.

 1. Knowledge of the life history and biology of the mite. The two-spotted
spidermite may invade strawberry fields from nearby non-crop plants, weeds, ornamen-
tals, ttees, or crop plants, eggplant, peas, beans, etc. The development of large
populations is dependent upon an adequate source of nutrition which is readily
available from the fruiting berry plant but which appears to be absent fron non-
fruiting vegetative plants. The mite lays tiny eggs which hatch into larvae,
these then progress through growth stages of protonymph and deutonymph before
reaching the adult stage. The cycle is completed in from 10-14 days in warm weather.
As large numbers of mites develop on plants, many will begin to migrate away from
their birthplace and in so doing form webs and groups of swarming mites on the tips
if leaves. Mlites may crawl across the ground or be blown by wind, moved by hand or
by machine. Under a good management program, the migratory stage of the population
should never appear since the desirable level of control to prevent damage is below
the level for migration.

 An estimate of 10-20 mites/leaf during Jan., Feb., and March is the tolerable
level to avoid undue damage to plants. The absolute average value tolerated depends
on variety; 'Sequoia' or 'Apollo' will tolerate more mites than 'Tioga' or 'Fla. 90'.

 Because mites inhabit the lower leaf surfaces it is necessary to look there
for them. Their many stages of development place undue burdens for control on
any material used, so the most advantageous use of all methods is desirable.

 2. Knowledge of basic approaches to control mites;
 A. Chemical toxicants
 The use of chemical toxicants proceeds logically from the 4-Rs of pesticide
use pointed out by the extension service.
 1. Right way seek out the right way to apply a toxicant with consider-
ation for formulation, concentration, or amount to be applied to best reach mites
on the lower leaf surfaces. Contact toxicants must touch the pest to be effective.
Sprays should thoroughly wet the lower foliage.
 2. Right amount use the material in accordance with the instructions
written on the label or instructions supplied by your extension service. Because
many formulations vary the concentration of technical material it is essential to
study each label to determine what amount to use.
 3. Right material make sure the material chosen for use is one that will
do the job, that it has not been stored too long and is still active. This choice
is one which must be made based on research data provided to the extension service.
Several compounds are available for use on strawberries. The next few remarks
pertain to recent field experience with these materials.

 Dicofol or Kelthane, a chlorinated hydrocarbon, is probably the most common
acaricide used for mite control. It has been used for several years, and conse-
quently, some populations of mites appear to be resistant to its action. In tests
of the two formulations the emulsifiable liquid gave better control than the
wettable powder.