Over the past couple of weeks, we have received several calls with questions regarding the sudden decline of apple trees. The most common question being, "What exactly is Rapid Apple Decline (RAD)?" This sudden collapse in apple tree growth is fairly new and there are still a lot of unknowns in regards to identifying the exact cause. One of the first signs of RAD is a curling of the leaves followed by a change from green to a yellowish-red color. RAD will start on one branch and spread to other branches which in turn causes tree death. The disease can cause death to whole plantings or just target one tree out of several. Grafted trees on dwarf and semi-dwarf rootstocks are affected more than trees on standard rootstocks.

What are the causes? First, there is no simple answer when it comes to pinpointing one exact culprit.  The majority of diseases can be attributed to viruses, fungi, bacteria, parasites, and many times to insect activity. Although, these factors might have some bearing on disease development no definite cause has been linked to RAD. Some pathologists have proposed environmental stresses such as winter injury, drought, and excessive amounts of rainfall in certain regions of the country as causes. Others have proposed that high-density planting of dwarf trees as the culprit due to tight plant spacing and excessive amounts of fertilizers and chemicals. Research is ongoing at NC State University and N.C. A&T State University trying to determine an exact cause, keep up to date by visiting the NC State Extension website for articles and the latest research data.