TO ALL OAK TREES IN ALL SEASONS PAINT PRUNING CUTS EVEN WHEN PRUNING APPARENTLY DEAD BRANCHES FROM LIVE TREES
New oak wilt centers correlate well with human activity, including Spring pruning, unpainted pruning cuts, and injuries to trees from string trimmers or heavy equipment, such as bulldozers or cedar shears. Several new oak wilt centers were started on the Ranch in 2002 from Spring pruning of oaks.
All oaks are susceptible to oak wilt. Red oaks are rapidly killed, and most infected live oaks will die from oak wilt without treatment. Other oaks might not die, however, they are likely to be less healthy and look less well than before the infection.
Unless the wound painting is “immediate”, the sap beetle (only the size of the head of a pin) can infect the tree with the oak wilt fungus spores that the sap beetle can carry. The practice of doing all the pruning before beginning the painting inevitably results in forgetting and missing a significant number of cuts. The Texas Forest Service recommends, that if you feel you must prune, then “Cut and paint, cut and paint...” for optimum protection.
While Spring (February through June) represents the highest risk for oak wilt infection from pruning cuts, the risk in Tierra Linda is significant throughout the year. Sap beetles carry more oak wilt spores in the Spring, but the sap beetles live about one year, and thus are always around. Spores can live longer than a year. We have so much oak wilt on the Ranch that sap beetles here are more likely to carry infectious spores than in less infected areas. Finally, the Texas weather can be warm enough in any season, including winter, to have spore-carrying sap beetles actively feeding on sap, and transmitting oak wilt spores to oak trees. The safest pruning times are on very cold winter days and the next safest times are on very hot days in late summer..
It is necessary to paint pruning cuts on live trees even when pruning “dead” wood because at some point the dead wood becomes live wood. It is virtually impossible to know where along the branch this change occurs. It is better to be safe than sorry.
Pruning paint in spray cans is rather expensive. An inexpensive, but equally effective, alternative is to purchase black automotive undercoating spray paint (available in Walmart) or any other spray paint.