QuestionHelp!! We planted six green giants (similar to Leyland cypress) in April. They are about 3 feet tall and get afternoon sun. I just noticed that all of them have interior branches that are turning brown as if they are burning. One branch fell off easily as if it is dead. What have we done wrong as I was told these were a very safe bet? We are in South Carolina. Thank you so much!!!
Answerit may just be delayed shock form the planting. If the inner needles are dropping and the other needles are green it more than likely not a disease. It could be spider mites. Spruce Spider Mite: Mites are not insects but are more closely related to spiders. Spruce spider mites (Oligonychus ununguis) are occasional pests of thuja. They are very small and not seen easily with the naked eye. They have piercing mouthparts that they use to suck plant sap. Their feeding results in speckling (formation of tiny yellow spots) on needles. Some needles may turn brown and drop off. With heavy infestations, fine webbing may be seen on the plant. Several seasons of heavy mite feeding may kill a thuja. Although most spider mites increase in numbers during hot, dry weather, spruce spider mites are cool-weather mites. Their populations peak during spring and fall, but drop dramatically during the heat of summer when predators feed on them.
To determine whether insecticide use is needed, it helps to know how many mites are present. Hold a white sheet of paper under a branch and strike the branch. The mites that are knocked off will be seen crawling around on the paper. If dozens of mites are seen per whack, serious damage can result. Continue to check population numbers at 7- to 10- day intervals. Pesticides labeled for homeowner use against spruce spider mite include insecticidal soaps and acephate + fenbutin oxide (Ortho Systemic Insect Killer or Ortho Orthenex Garden Insect & Disease Control Concentrate). Completely cover the foliage with the spray. As with any pesticide, read and follow all label directions and precautions before using.
If you are not sure I would call the local office of the SC Forestry Commission and ask one of their Foresters to take a look and even see if the SC Forestry Commission's Entomologist could check the trees. This is a free service. Their phone number should be in your local phone book.