ACORN PESTS

Acorns are usually attacked by two insect genera. They are the filbertworm (Cydia latiferreana) and several species of filbert weevils (Curculio spp.). Small closed blemishes are egg laying sites and can be found on viable acorns. Small holes, about the size of small pencil lead, are insect exit holes. Those acorns are usually quite chewed up inside and full of insect feces. Acorns that are light in weight or which deform easily when squeezed are usually abortive or insect damaged. If the acorns are intended for planting or for eating, the long used flotation test is as good as any. All acorns are put into a bucket of water. Those that sink are usually viable.

Birds seem to know the difference between a good and a bad acorn. When an equally large number of good and bad acorns are left out on a feeding tray for scrub jays, the birds almost always take only the viable acorns.

Various fungi can also colonize and decay acorns. Since the damp cool environment found in a refrigerator is similar to the winter environment provided by nature, the loss of some acorns kept in refrigerators is expected.

Nature compensates for bad acorn years by producing persistent seedlings in the understories of mature oaks. Seedlings can persist for years as only a few inches tall. During this period, they normally develop robust root systems, usually eight or more feet deep. Consequently, if the overstory tree or trees perish, the seedlings are in a good position to take off. The production of a massive root system while the seedling remains small is the reason that acorns that are germinated in pots, and should only be kept in the pots for one year.

Over the last 200 years or so, oak seedlings have had to contend with new environmental factors, such as hotter fires, livestock predation and introduced weedy species of grasses that can shade out the oak seedlings. Hopefully, man as the new environmental agent that has cause a decline in the rate of oak regeneration will get his collective act together so the our native oak trees do not disappear within the next thousand years or so.

                                                                                    Mike Kuhn

10-27-04