LEAF EATING INSECTS AND CATERPILLARS, whose presence is evident by their 
eating of foliage, readily controlled by spraying or dusting with stomach poisons such 
as arsenicals. DDT also seems to control, either as a spray or dust. 
LEAF HOPPERS are small greenish-yellow, flying insects which are very active in 
warm weather. Disturbing the plant will cause them to fly rapidly away and they can best 
be detected in this way. They are usually found on the under sides of the leaves sucking 
the plant juices, causing the edges of the leaves to turn yellow, eventually browning and 
destroying entire leaves at the bottom of the plants. Previous controls have not been 
very effective unless applied every two or three days. DDT will control them almost 
100%. 
RED SPIDER MITE, or simply red spider, are very small black and white to brown- 
ish, minute insects, nearly always found on under sides of the leaves. A magnitying 
glass is necessary to see these tiny insects but their damage is apparent by browning 
of the lower, and to lesser degree, the upper surfaces of foliage. Under sides of the 
leaves usually appear to have "rusty" areas and a sort of silky appearance. In the past 
they have not been serious pests of the dahlia except in isolated cases. However, if 
DDT is used as a control for other insects, it is likely that red spider mite will be very 
prevalent and cause much damage if not promptly controlled. To make matters worse, 
DDT kills the predators or parasites which normally feed on the mites. ‘'Dowspray-!7" 
applied according to manufacturer's directions has proven highly effective as a control, 
especially when combined with DDT. Dowspray-I7, as the name applies, is a spray 
material manufactured by the Dow Chemical Co., Midland, Mich. It seems far superior 
to all other standard red spider sprays. ‘'DN-269'' another DN compound has proven 
effective as a dust and much more effective than any previous dust for this purpose. 
Applications of spray or dust must be thorough and applied to the under sides of the 
foliage as well as the upper surfaces. NNOR may be substituted for Dowspray-1!7. 
TARNISHED PLANT BUGS are small plant bugs about a quarter of an inch 
long, brown mottled with shades of red and yellow. They are seldom seen on the plants 
as they fly away at the slightest disturbance. The bugs puncture the stalk, stems and 
buds, causing small black spots. Growth of stung part is severely checked, causing a 
shortening between nodes of the plant, shortening of stems, and causing buds to open 
one-sided or to fail to open at all. Badly infested plants are short, very bushy and 
never produce presentable blooms. DDT has proven highly effective in the control of 
this troublesome pest which has been very difficult to contro! before. 
THRIPS are very small, light greenish-yellow to dark brown insects which may be 
found by close examination of unfolded leaf tips and among petals of the flowers. 
A magnifying glass will aid in finding them as they are almost invisible to the naked 
eye. They cause malformed, dark spotted and blistered appearance of the leaves 
and often result in stunting of the plants. They are easily controlled with DDT. The 
Tarter Emetic and brown sugar spray, previously recommended, is still considered an 
adequate spray material. 
Considerable success in keeping down the ravages of pests has veen obtained by 
some growers by frequent, over-head watering, during the hottest part of the day. The 
water is turned on for a couple of hours every two or three days. This method is more 
practical on light, well drained soils than on the heavier soils which may become 
saturated to the detriment of the plant. 
DISEASES rob the plants of vitality, and in the case of some diseases, eventually 
destroy the plants. Control methods require destruction of all infected plants as the 
symptoms become apparent. Control of insects prevent spread. 
“MILDEW, common in the fall, is well-known. Control by dusting the under side of 
lower leaves with dusting sulphur, about Sept. Ist. One application will suffice for the 
season. 
_ After the frost has destroyed the plants in the fall cut the stalk off at the ground. 
An,ordinary saw is fine for this. If possible leave the clump in the ground for a week 
or ten days before digging. A long tined fork is best for digging the clumps. Be 
careful not to break or even strain the necks of the tubers. One person, with a fork, on 
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