Control. Spray with DDT to control vectors when leaves are fully
open and repeat 1 or 2 months later. European and Asiatic elms are
This has become a major threat to peach production;
it spreads to peaches from choke cherries around the orchard, al-
though the vector is not yet known. Diseased trees are lighter green with
red and yellow spots on leaf blades, the discolored areas often falling out;
young trees die; fruit shrivels and drops or ripens with a bitter taste.
Choke cherries should be eliminated. Chemotherapy, treating the soil
with chemicals to arrest the disease, has been effective in experimental
Another western disease, of tomatoes and other vegetables
and of flowers, has been found in New Jersey on dahlias and tomatoes. Tomato foliage has bronze, ringlike lesions, and the fruits are
marked with concentric rings of pale red, yellow, or white. Yellow ring-
spots appear on dahlia leaves, reddish-brown to purple spots on sweet pea
stems, and circular to oval spots on leaves. Calla lilies have spots and
streaks that are first white, then brown. Onion thrips and flower thrips
are the insect vectors, but they are hard to control. Rogue out diseased
specimens and keep down weeds.
TOBACCO and TOMATO MOSAIC.
This is the reason why you should not
smoke when you garden or work in the greenhouse. Incredible as
it seems, the virus lives through the curing of tobacco for cigars and
cigarettes and you can infect seedlings of tomato, pepper, eggplant, petunia, and other solanaceous plants just by handling them after touching
tobacco. Tomatoes have a typical mottling, with curling of leaves. Lily,
potato, and peach aphids transmit the virus.
Control. Don't smoke while working; wash your hands thoroughly
after smoking before transplanting, pruning, or tieing up plants in the
above list. Removed diseased plants immediately and scrub before touching healthy plants.
Like bees and sawflies, wasps belong to the order Hymenoptera, having
their 2 pairs of wings joined together. Most wasps are garden friends.
They pollenize our fruits and parasitize our insect enemies. We have
braconid wasps on tomato hornworms, ichneumen wasps that kill borers
in wood, Tiphia wasps for Japanese beetle grubs, etc. Sometimes this can
be carried too far, for we also have hyperparasites that kill our parasite
friends. Even yellow jackets who dispute the fruit we eat in the fall and
send us to bed with their stings when we inadvertently disturb them
are primarily useful, feeding on soft-bodied corn earworms and army-
worms. There are, however, two large solitary wasps that are distinctly