Spring of 2012 is already a challenge for tree care professionals.
The early warm (even very warm) weather is resulting in early leaf opening, early blooming and early insect development relative to normal historical dates for these events.
WHAT DOES THIS UNUSUALLY EARLY WARMTH MEAN FOR SPECIFIC PROBLEMS?
Crabapple scab. Normally we like to have one spray on before the leaves open and another after they open, but before the blossom. A third spray after the blossom completes the fungicide spray series and usually gives excellent control of scab. This year, it will be difficult to get two sprays on before the blossom and that may compromise the degree of control achieved.
Older crabs with severe recurrent scab problems may benefit from fungicide injections this spring along with the sprays. Crabs that are not injected that do not get good control of scab this year may benefit from fungicide injections this fall to help with next year's control.
Diplodia Tip Blight. This problem of pines also is best controlled with early sprays before the buds open up. Two sprays by May 1st is our usual rule of thumb, but this year we will probably be needing two fungicide sprays by April 15th. We use a combination of two systemic fungicides for this spray and always add a spreader-sticker.
Needlecast Fungi- Rhizosphaera in blue spruce and Dothistroma in Austrian Pines. The sprays for these fungi usually are done in mid-May and mid-June, but this year they may need to be earlier. We use chlorothalonil or Junction for Rhizosphaera and we use Junction for Dothistroma. A spreader-sticker is always added.
White Pine Weevil- This insect causes damage to the top leader in white pines and some spruces. Control by spraying usually requires sprays to the top of the tree very early in the season, usually by April 10th. This year that window for control may close by April 1st. Control may be possible with systemic acephate after that date. A good approach for future seasons is soil applied imidacloprid in the fall for control the next spring.
Spruce adelgids, Cooley on Blues and Eastern on Norways and Whites. Early spring sprays are usually needed. Fall imidacloprid can avoid concerns about weather surprises.
Dutch Elm Disease. Injections for Dutch Elm Disease are timed for May or early June and this year may need to be earlier.
Ash Borers. We usually wait until some leaves are appearing before we inject the ash trees. That may occur a couple of weeks earlier, so we may be able to start injections somewhat earlier.