CROWN GALL (Agrobacterium tumefaciens).
This is a very serious bacterial disease which shows up in the form of one or more rounded
galls with irregular rough surfaces at the crown of plants near the soil
line-often at the bud or graft union on roses-and sometimes with
smaller enlargements on the roots. On euonymus aerial galls are frequently formed along the vine. Crown gall affects more than 40 plant
families. It is very common on rose, raspberry, blackberry, and other
brambles, may damage fruit and nut trees, and sometimes affects young
shade trees, perennials, and a few vegetables. The bacteria are in the
soil and infect healthy plants only through wounds. They are spread
on tools in propagating operations and in cultivating, and sometimes are
carried in irrigation water. They come to the home garden in galls on
new nursery stock and after the original plant dies can live a year or
two in the soil ready to infect the healthy replacement.
Control. Be very suspicious of all rose, raspberry, etc., plants you buy.
If there are any galls, either large or small, do not remove them and
plant anyway. Burn the specimen or return it to the nursery for replacement. Not all enlargements are crown gall-some are merely excess
callus growth, but you cannot tell in casual observation, and it does not
pay to take a chance. Do not wound stems in cultivating.
Grasshoppers are the true locusts. They have biting mouthparts but
a gradual metamorphosis. The front wings are somewhat thickened
and narrow, with distinct venation, the hind wings broad and folded,
fanhke when at rest. Like crickets and the beneficial praying mantis
they belong to the insect order Orthoptera. In the West migrating swarms
of grasshoppers destroy all green things in their path. There control
measures are on a cooperative basis, with large-scale application of toxaphene, chlordane, aldrin, or poisoned baits. Even in the East grasshoppers
sometimes ravage foliage in home gardens, and dusting with chlordane
or other poison is advisable.
LEAF BLISTER, LEAF CURL
Different species of the same fungus are responsible for most of the
diseases characterized by overgrowth deformities known as leaf blisters
or leaf curl.
LEAF BLISTER OF OAK (Taphrina caerulescens).
Control. In experimental spraying Puratized Agricultural Spray applied in late February and early March (in North Carolina) has given
This is said to be the most
conspicuous disease of street oaks in the South and is an occasional
problem in other sections. Convex blisters on the leaves, up to 1/2 inch
across, grow together causing leaves to curl and drop. Trees are sometimes
killed with repeated defoliation.