Q&A With Eli Snyder

— Written By and last updated by

Q: The tips of my raspberry bushes are dying back. What is going on?
A: Tip die back of raspberries in early summer is often caused by the raspberry cane borer. Adult cane borers emerge in June, feed on foliage, and lay their eggs in raspberry cane tips.

rasberry cane

Two girdling marks near the tip of a raspberry cane indicate that a raspberry cane borer has deposited her eggs inside the cane.

The eggs will then hatch and make their way down the cane to just above soil surface where they will pupate and emerge as adults the following year.

Just before borers lay their eggs, they make two girdling cuts about ½” apart just below the tip. These distinctive marks are a good indicator that you have a cane borer infestation and that the borer has laid her eggs in the raspberry cane. When you observe this, cut the cane approximately 6 inches below the lowest girdling cut. This will prevent the larvae from traveling down to the root system later in the season and completing its life cycle in your raspberry patch.

Q: What should I do to control mosquitoes in my yard? Do I need to be concerned about mosquitoes in our area carrying the Zika virus?

A: The only reports of the Zika in North Carolina occur in people who have traveled to areas outside of the state where mosquitoes are known to carry Zika virus. The mosquito known to carry Zika, Aedes aegypti, has not been found in North Carolina for years, though monitoring efforts are underway track this mosquito.

The best prevention for mosquitoes is to remove any standing water from yards and homesites and reduce the number of sites that may collect water. Clean gutters regularly, flip over trashcan lids, dump out unused tires and clean up trash that may collect water. If you use a kiddie pool in the summer, be sure to change water or clean it regularly. Inspect your yard after a rainfall for sites that collect water. Make sure drainage ditches remain free from debris that prevent water from draining. Flush out birdbaths regularly with a hose. If you have a rainbarrel, cover it with a screen or solid lid. Dump the bases of potted plants after a rainfall. One of the more problematic species of mosquito in North Carolina, the Asian tiger mosquito, Aedes albopictus, a common mosquito in North Carolina, does not lay eggs in lakes in ponds; they prefer intermittent or temporary puddles with debris that can be used as nutrition for larvae.

If you are in an area with a lot of mosquitoes, use long sleeves, long pants, and an effective insect repellant to protect against bites. Ensure that screens for windows and porches fit properly, are secured, and are free of holes. Spraying for mosquitoes can be harmful to honeybees and cause losses for beekeepers or commercial honey production. Since a new generation of mosquitos can be produced in two weeks, spraying would have to be targeted and frequent in order to control mosquitos in a problematic area. It will cost you money but not control the problem if you continue to have standing water. For more information on insect repellants, see: https://www.ces.ncsu.edu/depts/ent/notes/Urban/repellents.htm

The North Carolina Department of Agriculture encourages beekeepers and pesticide applicators to avoid conflicts by using the Driftwach program. In this program, beekeepers can register the location of their apiary and those applying pesticides can check the registry to see if hives are located close to where they are planning to spray. Then the two parties can communicate about protective measures that may be needed during a pesticide application. If you are planning a pesticide application or would like to register your apiary, see: http://www.ncagr.gov/pollinators/Driftwatch.htm

Q: My apple trees have cedar apple rust. Should I spray them now?

A: Cedar apple rust is a fungal disease of apple and crabapple trees that requires both Eastern red cedar trees and apples or crabapples to complete its life cycle. Infection on apple trees will appear as small orange or brown spots on the leaves and sometimes blemished or misshapen fruit. Once apple trees are infected with cedar apple rust, it is not cost effective to spray them. The best thing to do is to rake up leaves when they fall this winter from the apple trees and scout next spring for galls on cedar trees. Grey or brown golf-ball like growths house the disease on cedar trees and during rains in the spring, these will transform into orange octopus-like galls. The galls release spores that will then infect the apple trees. You can reduce infection by removing the galls when you see them on cedar trees in early spring. Maintaining a regular spray program for other apple diseases will typically prevent cedar apple rust infection. For a spray targeting cedar apple rust, apply mancozeb or copper based fungicide two weeks after green buds show ¼” growth in the spring. Most of the damage caused by cedar apple rust is a reduction in photosynthesis from the rust spots on the leaves and some damage to the fruit, but heavy infections can lead to tree decline. If you are planting new apple trees, select varieties that have some resistance to cedar apple rust. For a list of heirloom varieties with some resistance, see: https://growingsmallfarms.ces.ncsu.edu/growingsmallfarms-heirloom-apples/

Don’t forget to stay cool and hydrated while you are working in the garden this summer. Contact the Caldwell Extension with other gardening questions at 828-757-1290, or stop by Monday-Friday 8 a.m.- 5 p.m.