DEAR JESSICA: I found this "cocoon" or whatever it is on some dead branches of my boxwood hedges. The hedges have not been doing well and I have had to pull a lot of them out. Can you help identify this? I would like to know if there is anything I can do to stop the boxwoods from dying.
-- Nancy L. Groben,
DEAR NANCY: That's the egg case of a praying mantid (insects also often referred to as mantises) -- beneficial all around. Leave it be and the mantids will protect your plants from pests.
I can't be completely sure why your boxwoods are dying without more information, but boxwood blight comes to mind, especially since your photo depicts bare dead branches. The aggressive disease, caused by the fungus Cylindrocladium pseudonaviculatum, has been present on Long Island for several years. It spreads quickly and doesn't respond to fungicides, so if your hedges are infected there's nothing you can do to save them.
The first symptoms of blight are the appearance of stem lesions and small, light-brown, dark-rimmed spots on leaves. The spots grow quickly and can eventually take on a bull's-eye pattern before leaves turn straw-colored and drop off the plant, leaving stems bare, which is when the stem lesions become visible. (Discolored leaves do not indicate blight; neither do branches with dead tan leaves still clinging to them.)
The pathogen thrives in damp, warm weather, so if conditions are right and the pathogen is present, the spores can multiply quickly and spread from one plant to many others by wind or rain. And it can survive for up to five years, even over winter, so if infected plants are removed, new boxwoods should not be planted in the same spot.
Check the undersides of remaining leaves for a white powdery or sticky substance, and if present, bring samples (as well as those of dead, bare branches) to the Cornell Cooperative Extension diagnostic center in East Meadow (832 Merrick Ave., 516-565-5265) or Riverhead (423 Griffing Ave., 631-727-4126).
Don't jump to any conclusions, however, because blight can mimic several other diseases. Leave the diagnosis to the experts.
DEAR JESSICA: Our peach tree has leaf curl. Is there anything that can be done to get rid of it now? I read your column years ago prescribing the use of Bonide in spring and fall. I sprayed in the fall after the leaves had fallen. I guess I should have sprayed again in spring, but hindsight is 20/20. Can anything be done before fall?
-- Ronald Palermino,
DEAR RONALD: Peach leaf curl is a disease caused by the fungus Taphrina deformans. It is commonly found on peaches and nectarines in unsprayed home gardens. Symptoms are first noticed in spring, when leaves become red-tinged and thick before puckering and curling. Severe infections can diminish crop yield. The best prevention, of course, is to plant resistant cultivars, but as you point out, hindsight is 20/20.
You were right to treat trees in autumn after the leaves had fallen. A single treatment with a fungicide containing fixed copper or chlorothalonil is often all that's needed, but we had an extremely wet winter, so a second treatment just before leaves emerged would have been advisable. Unfortunately, there's not much you can do now. If the tree's limbs are crowded or could use some thinning, do so in fall and then spray again, ensuring that every part of the tree is completely drenched to the point of dripping. Repeat in late winter or very early spring.