Many times we have been asked what trees should be replanted in an area where trees have failed. Replacing with the same species that has died out is not a good idea unless you can identify why your trees that you are replacing failed. Colorado spruce should be replaced them with Black Hills spruce or Norway Spruce. The clump white birches that are failing are likely being attacked by borers, which are nearly impossibe to control once established. If you can locate a certified arborist, you might want to have the trees treated to prevent destruction.
In our area many landscapes are hard hit by bagworms. If you are replacing stock that is destroyed by bagworms, make sure host trees that also are infected are treated. Then replant the same type of tree or plant.
The only pests that I really worry about are bagworms. CHECK YOUR ORNAMENTAL SHRUBS FOR BAGWORMS. These can defoliate your nursery stock.
June is time to start looking. It's time to inspect junipers, arborvitae and pines .... even broadleaf shrubs and trees like rose, sycamore, willow, beech, maple, elm and black locust.
The bagworm gets its name from its spindle-shaped bag that the caterpillar carries around as it feeds on your plants.
The bag is woven from silk and is covered with bits and pieces of leaves and twigs from the your plant. The bag of a worm feeding on juniper will not look the same as the bag of a worm feeding on willow. Ultimate size will be slightly over one innh and hang down on the plant.
The larva itself is dark brown with a yellow head and yellow and black spots on the body. You will have a tough time opening up the bag to see it. Adult females are wingless and lack usuable legs, eyes and antennae. They are almost maggot-like, and seldom seen. Adult males are typical moths, black and densely hairy. Wings are nearly clear with a span of about an inch. I have never seen one in our nurseries only in pictures.
The problem with bagworms is that they defoliate them. Heavy populations kill will an ornamental arborvitae and juniper. But control is possible.
The larvae hatch from overwintering eggs in the spring usually in May. Each larvae spins a silken bag that it carries about while it feeds on the plants foliage. As it inlarges, the larva enlarges the bag as it keeps adding bits of foliage as camouflage. Many people don't know that the bag is there because it looks like a seed pod on shrub or tree.
Because the larval stage is the only mobile stage, one bush can have a high population and another one several feet away can be free of bagworms. Several parasites feed on bagworms. Birds eat them and the worms can be killed by low winter temperatures.
A very effective control is to pick the bags off the host plant in the winter.
Young bagworms are especially sensitive to the bacterium Bacillus thuringiensis. This is commercially available under the trade name Dipel.
The disease caused by the bacterium affects only the moth larvae and is very safe to use. Always read and follow label directions before treatment. Best results will be obtained when spraying in late afternoon or early evening.
Treat early when you first notice the bagworms, since small larvae are easier to kill. Other insecticides which will control bagworms include acephate (Orthene) and carbaryl (Sevin).
There are some mites, midges and bettles that can be problematic. Rusts, make the tree unsightly don't harm this tree but can effect other plants such as pines and apple trees. If you are looking for a hardy, native evergreen, for a constrution or landscape site that needs little care, this is your tree. We have plenty of seedlings and B&B trees upto 6' ready for your pickup. Its best to call in advance if you want more than 10 as we will dig them fresh for you.