As the growing season draws to a close, it's time to think about the fall preparations that will help bring our tree and small fruits through the cold months ahead. While there is not a great deal that needs to be seen to, making sure these few important chores get done will set the stage for a bountiful harvest next year.
A little care this fall will help your fruit trees weather the winter months in top condition.
Some time spent in garden cleanup now will pay big dividends in fewer insect and disease problems down the road. Pick up and dispose of all fallen fruits to provide fewer places for insects and diseases to overwinter. Apple maggots are a good example. The larvae of these troublesome pests tunnel into the fruit where they remain until it drops, and then they crawl out to pupate in the soil for the winter. If you scoop up the dropped apples regularly, you'll dispose of the apple maggot larvae at the same time.
Raking up and disposing of leaves also helps to reduce problems. For example, apple scab is a fungal disease that overwinters on infected foliage. Getting rid of the fallen leaves reduces the amount of fungus that will be around to cause problems next spring.
Should you put these collected leaves and fruits in your compost pile? Most home compost piles don't heat up enough to reliably kill off pests and diseases. If you have some obviously infected or infested plant material, it's probably best to dispose of it off-site unless you are sure you are making ″hot″ compost. If you can, bring the material to a collection point for a municipal composting program, since the compost in most large-scale operations heats up to high enough temperatures to neutralize pest problems.
Protect Fruit Trees from Critters
There are few things that meadow mice (actually voles) like better as a winter snack than the tender bark of fruit trees. Voles do their damage by girdling the bark at the base of the trees; if they chew through it around the entire circumference of the tree, the tissues that conduct water and nutrients in the tree are severed and the tree dies. To make your trees less hospitable to voles, mow grass and vegetation around the trees so that the voles have less protection from predators. Pull back mulch from around the tree bases in early fall to keep the voles from setting up housekeeping there. Construct 18-inch high cylinders made of hardware cloth, a type of wire screening available at hardware stores, to wrap around the lower portion of the tree trunks. Push the bottom few inches of the cylinders into the soil so the voles can't tunnel under. You can also use purchased white plastic spiral mouse guards for vole protection. The hardware cloth guards can be kept in place all year-round (just make sure they are not constricting the trunk as it expands as the tree grows), but the plastic guards should be removed each spring to keep it from providing a haven to borers.
Rabbits and deer also regard fruit trees as tasty treats. Protect trees from rabbit damage with the same hardware cloth cylinders that you use to fend off voles. Just remember that in many parts of the country rabbits will be sitting on top of the snow when they dine on your trees, so make sure the cylinders are tall enough to extend a foot or so above the average snow depth if rabbits are a problem in your area.
Deer love to browse on fruit buds in winter. Repellents may give some protection but will need to be renewed periodically over the winter. The best (and unfortunately most expensive) solution is appropriately designed fencing.
Remember that raspberries produce biennial canes that live for two years. Summer-bearing raspberries produce non-fruiting primocanes the first season. In their second season of growth, these canes (now called floricanes) flower, bear fruit, then die. You can recognize the dead or dying canes by the empty fruit stems, yellowing foliage, and rough, silvery brown bark on them. Prune out these spent two-year-old canes as close to the ground as you can get. Fall is a good time to do this, although the spent canes can be cut out any time after they have finished bearing up until late winter/early spring before new growth begins.
Everbearing (also called fall-bearing) raspberries produce a crop of berries on the tips of the first-year primocanes, then go on to set another berry crop farther down on the second-year floricanes, after which the canes die. If you manage your berries to produce both a fall and spring crop, prune off the tips of the primocanes in the fall after they have finished fruiting. Then treat the second-year canes as described for summer-bearing raspberries above. Some gardeners choose to harvest only one bigger fall crop. To do this, cut back all the canes after the fall harvest when the plants are dormant. Next year, all the canes in the bed will be primocanes that will fruit at their tips in late summer and fall.
Fall is also a good time to thin out your raspberry patch so that it doesn't become overcrowded. When the plants are dormant, thin out the one-year-old canes to about 6 inches apart, leaving the thickest and tallest canes. Give the bed a good weeding, renew the mulch, and you'll be set for next spring.
In cold winter areas strawberries generally need some protection over the winter to prevent injury from the cold. In late fall, after two or three hard frosts but before temperatures go below 20 degrees F, put down a 3-6 inch layer of insulating material over the strawberry bed. The traditional material for mulching is -- you guessed it! -- weed-free straw. If you're concerned that the wind will blow your straw mulch away, hold it in place with a covering of chicken wire anchored to the ground. Don't cover your plants too early. They need exposure to the falling temperatures and shortening days of fall to develop all of their natural winter hardiness.
A newer means of protection is heavy-weight row cover fabric, available from garden stores. Lay the fabric over the bed and anchor its edges securely with soil, rocks, or some other heavy material. If the fabric is treated carefully, it will usually last for three or four winters.
Remove coverings in the spring when about a quarter of the plants have begun new growth. Rake the straw into the paths or keep the row cover fabric handy to recover plants if spring frost threatens.
As the leaves of your blueberry plants put on their lovely wine-red fall color, hold off on any pruning until after plants are completely dormant. Late-season pruning can stimulate the plants to put out new growth that won't have a chance to harden off before cold weather and is likely to suffer winter damage.
Pick off and dispose of all fruits still clinging to the bushes and gather up any fallen berries. This will help reduce problems next season from mummy berry, a disease that causes fruits to shrivel and turn into hard ″mummies″ on the plant. It's also a good time to renew the layer of mulch around the base of your blueberries. This gives the roots some winter protection and buries any infected fruits you missed. Sawdust, wood shavings, shredded bark, pine needles or chopped leaves are all good blueberry mulch materials.