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Spider
Mites
(Twospotted mite is the most common spider mite)
|
Adults
are about 1/50" long, have eight legs, and are light
tan or greenish in color with a dark spot on each side,
which
looks like a saddle. |
Feed on underside of foliage.
Reduced plant vigor, water loss and
premature defoliation. Usually increase during harvest.
|
Continue to monitor
spider mites and predator mites closely in mid- to late-
August. Spider mites can increase in mumbers rapidly during
mid - late August. |
Apply miticide
if populations reach 25 mites per leaflet before September. |
Miticide application
if threshold is reached. Keep plants adequately irrigated. |
Fields that have been sprayed should be
sampled 5-7 days after the application. |
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Raspberry
Crown Borer |
Adult,
egg, and caterpillar stages may be present during this
time. Adults clear-winged moth
looks like a black and yellow wasp. Caterpillars range
in length from 1/4" 1" depending on age. |
Caterpillars
tunnell in canes and crow area, weakening plants.
|
Check lower canes
and crowns for presence of caterpillars. |
Seemingly low levels of infestations can
develop rapidly into a high population. |
Insecticide application to lower canes
and crown area. October is preferred timing. If damage
is present, treat for two consecutive years to obtain
control. |
Check canes next season. |
|
Plant Parasitic
Nematodes |
Microscopic
wormlike organisms which damage roots, resulting in stunted
unproductive
plants. The two most common species are Pratylenchus
penetrans (root lesion) and Xiphinema bakeri (dagger
nematode). |
Feed
on and damage roots. One species of dagger nematodes,
(X. americanaum)
transmits Tomato Ring Spot Virus. |
Soil and root
samples from good v. poor areas in a field should be sent
to a laboratory and analyzed for population size and makeup. |
Rough
threshold: 250 root lesion/250 cc of soil. No threshold
established
for roots. Presence of X. americanum at any density
is cause for concern. (1 pint = 454 cc./cubic centimeters) |
Check soil before
planting raspberries. Avoid planting infesed fields or
consider fumigation. Soil applied nematicides may be available
for controlling root lesion nematodes in established fields
in the fall when populations are highest. |
Re-sample infected
areas after treatment. Sample fields on a regular basis,
at least once every two ears to determine trends in poplation
density. |
