Insects and Trees
There are many different species of spidermites. They attack evergreens and deciduous plants. Populations can grow at a very fast rate if weather conditions are right.
Hot, dry conditions are often associated with population build-up of spider mites. Under optimal conditions (approximately 80 °F or 27 °C), the two-spotted spider mite can hatch in as little as 3 days, and become sexually mature in as little as 5 days. One female can lay up to 20 eggs per day and can live for 2 to 4 weeks, laying hundreds of eggs. A single mature female can spawn a population of a million mites in a month or less. This accelerated reproductive rate allows spider mite populations to adapt quickly to resist insecticides, so chemical control methods can become somewhat ineffectual when the same pesticide is used over a prolonged period.
Spider mites are less than 1 millimeter (0.04 in) in size and vary in color. They lay small, spherical, initially transparent eggs and many species spin silk webbing to help protect the colony from preditors; they get the 'spider' part of their common name from this webbing.
Light browning of needles with apparent webbing is a tell tale sign of spidermite activity. Early identification is paramount to control. Spidermite kill plants. Dormant oil is used to control eggs in the Spring. Severe infestation will require several crawler spray applications during the Summer months. The next season crawlers sprays can be reduce as control gets better. After several seasons the application can be reduced to dormant oil in the Spring.
Hemlock Woolly Adelgid
The insects came from Asia. They have no natural predator in New England area. The adelgid is a small aphid like insects that threatens the health of Eastern Hemlock, Tsuga Canadensis, and Carolina Hemlock, Tsuga Caroliniana. Decline and mortality typically occur within four to ten years after infection. If conditions are right for the insect this can happen in three to six years.
The Hemlock Woolly Adelgid is small, less than 1/16 - of an inch. It varies from dark reddish brown to purplish black in color. You can not see the insect with the naked eye. When mature it produces a covering of wool like wax to protect itself and eggs. This also stops the eggs from drying out. This "wool covering" can easily be seen and in early stages may look like bird droppings. In fact birds are the main method of dispersal for the insect. Do not hang bird feeders in your Hemlocks this will only increase your chances of getting the Hemlocks infected.
Infections will start at the bottom needles of the plant. HWA like it cool. HWA are parthenogenetic, all individuals are female with asexual reproduction. HWA has six stages of development, the egg, four nymphal instars , and the adult. The Winter generation develops from early Summer to mid Spring the following year. June-March. The Spring generation develops from Spring to early Summer. March - June. HWA will lay up to 100 eggs in the Spring generation. Winter generation can lay up to 300 eggs. Populations build quickly. HWA go dormant during the heat of Summer. They do not actively feed until cooler temperatures occur.
Dormant oil applications are generally the most efficient way to control HWA. Spring and Fall application in heavy infestations. A systemic insecticide may also be used.
Gouty Oak Gall
Most leaf galls on oak cause little or no harm to the health of a tree. However, twig or branch galls may cause injury or even death to a heavily infested tree. Two common species of twig gall-producing insects are the horned oak gall wasp, Callirhytis cornigera (Osten Sacken), and the gouty oak gall wasp, C. quercuspunctata (Bassett).
These species are in the insect family Cynipidae. Both the horned oak gall wasp and the gouty oak gall wasp are known to occur from southern Canada to Georgia. Each of these galls may be diagnosed by their unique characteristic size, shape, and color.
There are a variety of gall-forming species of small wasps that commonly infest oak, Quercus spp .
In early spring a tiny wasp of the cynipidae family emerge from woody stem galls. The females lay eggs on the veins of the oak leaf buds. Male and female wasps emerge from these tiny, blister type galls on the leaf vein about mid summer. Mated females deposit eggs in young oak twigs. The next spring small swellings develop on the twigs and enlarge over the next two or three years. The galls provide protection, food, and shelter for the developing larvae. When the larvae reach maturity, the horned galls developed small spines or horns, Gouty oak galls have no spines, they are most prevalent in our area. An adult wasp emerges from each gouty / horned and another life cycle of wasps begins.
In the past we have not tried to control this pest. In the past the gall insect has only attacked limited Oaks on a property.
We are now seeing numerous out breaks of this pest on many properties. " Mother Nature" is changing, this pest is becoming much more prevalent then it has in past years. If caught early a systemic foliar application of insecticide will stop the eggs in the leaves in the Spring. A Fall soil injection of systemic insecticide for one year. This program is only recommended for feature trees.