Agriculture Reference
In-Depth Information
prunes, nectarines, and apricots. They overwinter as mature larvae in tunnels
near the soil surface. The larvae pupate on the soil surface and emerge as
adults, typically from June to September. The adults lay eggs singly or in
masses near the soil line, and the young tunnel into the trunk and large roots
near the soil surface.
Young trees can be girdled or killed by a single larva, and older trees
can be damaged. Mounds of sawdust-like frass and small holes, often with
gummy exudates near the soil line, indicate that the pests are present. You
can protect trunks by tightly wrapping them with plastic or metal that ex-
tends several inches into the soil and fits tightly against the trunk for several
inches above the soil. Heavy-duty aluminum foil works well for this purpose.
For small plantings, excavate about 3 inches into the soil around the trunks
and kill individual larvae using a wire to probe into the feeding holes.
To reduce egg laying and feeding in the Pacific Northwest, horticulturists
recommend applying Surround to the base of trees in early spring. Making
weekly applications of
Bacillus thuringiensis
to the base of the trees from
July through August can kill the larvae as they begin feeding on the trunks.
The parasitic nematode
Steinernema carpocapsae
can help manage these
borers when applied as a drench to the lower trunks and soil during warm
weather in spring and fall. You can also use mating disruption twist ties (Iso-
mate) to manage pest populations.
Peachtwig Borer
Peachtwig borer is an introduced moth pest that attacks twigs, shoot tips,
and newly emerging shoots of peaches, plums, and apricots. The pest over-
winters in limb crotches inside chimney-like structures called hibernacula,
which are made up of sawdust-like frass. The larvae emerge early in spring
and begin feeding on newly emerging shoots before pupating in protected
areas on the trunk or inside fruits.
The adults emerge to lay eggs on new shoots, fruits, and young branches,
and there are multiple generations each year. Later generations of larvae
feed inside the fruits, usually entering near the stem. Applying dormant lime
