Agriculture Reference
In-Depth Information
may remain firm during cool weather or become soft and watery as temper-
atures rise.
Infected leaves develop spots up to
⁄
4
inch in diameter with dark outer
1
rings and lighter-colored centers that create a frog eye appearance. Sunken
lesions develop on twigs and form cankers up to 3 feet long or more on
branches. The cankers may appear to be no more than rough areas on the
bark, or they can be open wounds with raised edges.
Management.
Good sanitation is the key for controlling these diseases.
Prune out cankered wood whenever you find it because it is an important
source of inoculum. To control both black rot and white rot, it is very im-
portant to carefully remove fire-blighted wood, as the pathogens easily enter
blighted wood. Remove all prunings from the orchard and burn them. If you
cannot remove the prunings, use a flail mower to chop them into small pieces
that will decompose quickly.
Follow good nutrition, pruning, and pest and disease management pro-
grams, as we have already discussed, to maintain healthy trees that are res-
istant to the development of cankers. Plant rootstocks and varieties that are
reliably winter-hardy in your area because the cankers develop more easily
in winter-damaged wood.
Fungicides are an important part of an integrated program to control
black rot and frogeye spot. Begin applying fungicides during bloom. If lesions
develop on the fruits or leaves, repeat applications before or immediately
after spring and summer rains. In the Mid-Atlantic and southeastern states,
you will need to apply fungicides from bloom through harvest.
Bitter Rot of Apple and Pear
Also known as anthracnose on peaches and nectarines, bitter rot of apple
and pear is widespread and can cause severe damage in warm, moist condi-
tions. Apple and pear are most often affected, and infections are more com-
mon on fruit than on leaves and shoots.
