Ah, April. A great, transitional month where you never know what weather you’ll be blessed with. It was 73F/23C the other day and then 34F/1C a few days later. Sigh.
I hope these Monday Memories are interesting or just a ‘LIKE’ and move on.. 😉 There are just so many things to watch for in the landscape and small windows to treat in, you don’t want to miss them.
If any of your evergreens look a bit brown this time of year, it’s time to investigate why the tree looks this way. If you don’t see any pen tip sized holes in the trunk, then there is another reason other than borers that the tree died. However, if you see holes, these dead trees need to be removed before mid-April, when the adult borers emerge and fly to other trees. I’d highly suggest doing this if you have other pines and spruce on your property.
Insecticides should be applied during the two vulnerable times in the ZPM cycle. These times are late to mid-April, as the over wintering caterpillars become active, and in August, when the female moth has just laid her eggs and the caterpillars are searching for over wintering sites. Indicator plants for these spray times are when the saucer magnolia is in pink bud to early bloom, or in mid to late summer when panicle hydrangea is pink. Preventive insecticide sprays should be applied as a drenching spray to trunks in mid to late April.
Managing Diplodia tip blight focuses on tree health, sanitation and fungicide applications. Providing proper care helps suppress the disease. Removal of diseased cones from the ground helps, but is not practical in large stands. Pruning of infected tips will aesthetically improve the tree, but will do little in the stop of the disease. Severely infected trees should be removed. A fungicide spray program needs to be implemented in the spring and includes at least three applications. Make the first application just prior to bud break.
The “rule of thumb” for the Upper Midwest is to avoid pruning or wounding oaks during the months of April, May, and June. Nitidulids, carrying spores of the fungus, can be attracted to fresh wounds on oak trees. When nitidulids visit these wounds spores can be transferred to the oaks, initiating oak wilt disease infections. To avoid infection, all necessary wounds to an oak in the spring should be treated immediately with wound dressing or paint. (this is the ONLY time I will recommend wound dressing, normally a no-no!!) New symptoms of oak wilt disease usually are apparent in July and August.