The nearly continuous cloudy and rainy weather we've been experiencing this spring (2009) has been great for our water table, but it has brought with it some problems in the garden.
Constant wet and humid conditions in the garden can promote disease problems like leaf spot, Botrytis, and root rot. Some of the plants that have been affected most are peonies, hosta, and iris. Other unwanted pests that just love these rainy, moist conditions are the slugs and snails; for them the wetter the better!
Leaf spot appears as blotches or spots on the foliage and sometimes on the stems and flowers as well. This disease is most often caused by a fungal infection early in the growing season and is easily spread during cool, wet weather. The fungus that causes leaf spot can overwinter in dead leaves and other debris in the garden so proper clean-up in the fall or early spring can greatly reduce the incidence of this disease. Leaf spot can be controlled to some extent by spraying with an approved fungicide such as Mancozeb or Copper Fungicide. Always read and follow the label directions when using any fungicide.
Botrytis or gray mold is another fungal disease that becomes prevalent after severe late spring freezes or during periods of cool, rainy weather. It can be especially damaging to plants when wet, humid conditions continue over several days. Unfortunately, we've experienced all of the above weather conditions this spring! Botrytis appears as a grayish or brown powdery mold covering flower buds, leaves, and stems. It affects many different perennials but is especially common on peonies. As with leaf spot, botrytis overwinters in dead leaves and other plant tissue so it is important to remove all plant debris from the garden in the fall. If you notice botrytis on buds, leaves, or stems, carefully remove the infected plant tissue, place it in a bag and discard it in your trash. Never do this while the plant is wet or you risk spreading the disease to other healthy plants. Spray with a fungicide such as Daconil, Mancozeb, or copper fungicide. Always read and follow the label directions when using any fungicide.
Root rot caused by fungal infections can become a problem in wet, waterlogged soils. Symptoms are the wilting and subsequent death of the plant. This problem shows up more during extended periods of wet, rainy weather. Prevention is the best medicine in this case. Many soils are severely compacted to the point that they are denser than concrete! Be sure to prepare your soil well before you plant, adding plenty of organic material so that the soil is loose and well drained. Root rot can be treated with an approved fungicide. Always read and follow the label directions when using fungicides.
These guys really like the weather we've been having and they've been having a field day feasting on our plants! Damage can be seen as holes in the leaves of hosta, which they especially like, and other perennials and annuals. Slugs and snails can be controlled safely (even around children and pets) using Sluggo which contains iron phosphate. Always read and follow the label directions.