For one thing, we certainly haven't had to water our lawns or gardens! That's been very nice. Most plants, including trees and shrubs, have thrived with this excess amount of rain and have come through the spring much healthier than they have been for a while under our previous drought conditions.
Excessive Growth: One thing we are noticing in the Viette gardens is that many of the perennials and even some trees and shrubs have responded to the excess rain by putting on excessive growth. Copious amounts of water, combined with a lack of sunlight, has caused this extra growth, mostly at the tips, to be willowy and leggy, and not as strong. While this isn't necessarily a problem, it can be a little unsightly and cause the plant to flop or even break.
Tip back the longer shoot tips that seem to be very leggy. This doesn't mean to shear the whole plant, just cut back the longest shoots (no more than 10-20%) to right above a node to make the plant or shrub look neater.
Thin out 10% to 20% of the interior branches of very densely growing shrubs and understory trees in order to allow more light to reach the center. This will reduce disease problems by increasing air circulation and sunlight. Use caution when pruning back some evergreens like pines and Blue Spruce which will not regrow well after severe pruning. Only cut back up to the last 2 or 3 years of growth.
Disease Problems: We have also noticed an increase in fungal diseases in our gardens. This has been the subject of many calls to the nursery as well. The cool, wet weather has definitely created more disease problems.
Powdery mildew has become a problem on some plants in our gardens - especially on some of our non-resistant garden phlox. Wide spacing and thinning of perennials and shrubs, as well as planting resistant varieties, can help reduce the incidence of mildew in the garden by allowing better air circulation. Sometimes an application of a fungicide is necessary. Try sulfur, Bonide All Seasons Oil, copper fungicide, or Daconil. Always read and follow the label directions! If you prefer not to spray, you can just live with the problem or even cut back the affected plants, discard the trimmings in the trash, and let new fresh growth come up.
Tomatoes have been struggling with disease problems this year with the wet and cool weather. We have gotten numerous calls and discussion board posts about leaves on the lower branches of tomato plants turning yellow, brown spots on the leaves, and lower leaves curling. These are all symptoms of fungal diseases. One way to reduce the disease problems is to plant disease resistant tomatoes. Heirloom tomatoes, while very flavorful, are not disease resistant and are susceptible to anthracnose, verticillium, fusarium, and alternaria (early blight).