Pruning:
Pruning is generally not recommend beyond mid to late summer in order to allow trees to harden off before cold weather arrives. Late pruning can result in new, tender growth unable to survive cold temperatures.

However, try to always carry your pruners with you as you walk through your fields. Although the time of year may not be ideal for extensive pruning, take the time to prune out a dead, diseased, or damaged branch anytime you see it. Often it is better to remove it when you see it than to leave it and forget about it when it is time to prune again. Another option is to carry flagging tape and mark trees that have a defect to be pruned out during winter pruning. See pruning out insect damage below.

Insects:

Photo:
Female cicadas slit the bark on pencil-sized twigs and lay their eggs inside the wounds April - June. Shown on redbud and cistena plum.

Why is this important now?

The most serious consequence for nurseries is the injury to permanent branches which comprise the basic structure of the tree. Cicada egg laying injury causes a weak point so branches that are gathered together and tied during harvest and shipment are broken very easily. When damage is extensive growers may have to remove 1 to 2 years of growth in order to develop usable branches on a finished product. This may mean that the trees near the end of production may not be marketable during the fall after emergence or the next year. Any remaining cicada damage should be pruned out before growth resumes next spring to avoid developing damaged branches into the permanent canopy of the tree.

Note: To maximize the impact of pruning out cicada damage, prune within 6-8 weeks after the damage is done to eliminate the damaged branches and remove the eggs before they hatch.
The next statewide periodical cicada emergence is expected in 2004.

Source: U.K. Entfact 446, Periodical Cicadas in Kentucky

Diseases:
Powdery mildew should be controlled on dogwoods to reduce stress and maximize growth. The fungus causing powdery mildew overwinters on leaf debris. Therefore, if powdery mildew has been a problem, consider an additional fungicide application before leaf drop.

Effective fungicides include: azoxystrobin (Heritage), fenarimol (Rubigan), myclobutanil (Eagle, Immunox), propiconazol (Banner Maxx), thiophanate-methyl (Cleary's 3336), and triadimefon (Bayleton, Strike). When using fungicides for powdery mildew management, be sure that dogwoods are listed on the label and carefully follow all label directions. See Nursery Update #1.

Note: Cornus florida 'Cherokee Brave' has consistently shown excellent resistence to powdery mildew as have many C. kousa and C. florida and C. kousa hybrids.

Source: Kentucky Pest News, Article 925, July 16, 2001; SNA article "Winter Survival and Source of Primary Innoculum for Powdery Mildew of Dogwood"; NCSU Ornamental Disease Information Notes-023, Dogwood Diseases.

Cultural:
Check the pH of your fields this fall. Instances of likely manganese deficiency on maples, particularly red maples, have been seen lately. This is commonly due to a high pH. Manganese is most available at a pH 6.0 or lower. Manganese is necessary for making chlorophyll, which is essential in photosynthesis.

Source: U.K. Pub. ID-84, Iron Deficiency of Landscape Plants. Diseases of Trees and Shrubs. Sinclair, Lyon, and Johnson. Cornell University Press.