The USDA IR-4 project works to expand product labels to fulfill the needs of ornamental producers and landscapers. The survey takes 3-4 minutes and will help steer IR-4 funding toward the pests and diseases most important to you. There is also a project request form where you can give more specific documentation of your needs. In the past they have funded work on armored scale, soft scale, flea beetles, and other hard to kill pests. If these critters are at the top of your list please let them know.
Emerald ash borer has the potential to kill all ash trees in infested areas. You can read the
original press release for quarantine information. I will post soon about management options. Generally though, as EAB spreads municipalities should plan on losing all ash trees that they cannot afford to treat each year.
Here is the link. Happy reading.
Tea scale, Fiorinia theae, is common on camellias. It is an armored scale that lives on the
underside of leaves. You can find it on almost any camellia by looking for inner leaves that have yellow spots on top. When you turn it over you will see tan canoe-shaped scale covers and some white fluff from the males. These are tough to treat because the heaviest infestations are often deep within the foliage of large bushes. You can find a Insect Note with more information and recommendations here.
Euonymus scale has three generations per year in North Carolina the first of which we
reported on in the spring. It is best to treat euonymus (or any) scale in the crawler stage. So if you forgot in the spring or didn’t get sufficient control, now is your second chance. Crawlers are active at research sites on campus and in Raleigh neighborhoods. In the first generation crawlers come out all at once but become less synchronized in second and third generations. Thus you may find all developmental stages present at this time. There are many predators that feed on scale insects such as the lacewing larva in this video. However, euonymus scale still tends to reach damaging levels once established. There are a number of products that can be used to treat armored scale. We have found neonicotinoids Safari, Flagship, and TriStar to be very effective also plant growth regulators Distance and Talus. Note that imidacloprid is not labeled for or effective against armored scale. Please check the updated insect note for recommendations.
Although the cool season is over, damage from cool season mites is beginnig to appear. I
found this cherry laurel with extensive mite stippling. On the leaves there were no active mites just lots of eggs. This is the last stand of southern red mite for the summer. They spend the hot months as eggs then come out again in fall. They feed in spring but often the damage does not become apparent until the plants face some stress in hot weather. So be sure to monitor these plants in fall. Horticultural oil may help smother the eggs but be careful in hot weather.
In North Carolina, the most important cool season mites are the spruce spider mite (Oligonychus ununguis) and southern red mite (Oligonychus ilicis). These are among the earliest and most damaging pests in nurseries and landscapes. As their name implies, cool season mites are active in spring and fall when they suck fluid from cells on plant leaves and needles. In hot summer months these mites are dormant. However, it is summer when their damage becomes apparent as chlorophyll bearing cells die. Thus, by the time plants exhibit aesthetic damage the mites are gone and treatment is wasted.
Scout plants that had mites or mite damage the previous year as they are likely to have them again because the mites have overwintered as eggs. You can identify plants that had mite last year by looking for fine stippling damage on the old leaves. Turn them over and look with a hand lens for silk webbing, shed skins, and mites. On broadleaf evergreens, look on the underside of leaves for the southern red mite. The most efficient method of scouting for cool season mites (and other mites) is to hold a piece of white paper or a paper plate below a branch and strike it with a pencil or stick to dislodge arthropods. Spider mites will appear as tiny moving specks about the size of the period at the end of this sentence.
Read our recent article about spider mites
from Nursery Management. For more information and control options consult the NCSU Insect Note.
If you read my blog you know that I am not against insecticides but I am against the misuse
or unnecessary use of insecticides. With cicadas emerging, big box stores are overflowing with insecticides promising to kill periodical cicadas. This may be true. If you take a particular insecticide off the shelf and pour it on a cicada it will kill it. But these products will not ‘control’ cicadas. What are you going to do stand in your yard sprinkling every cicada you see? There are millions upon billions of them. Your dog probably stands in the yard eating them one at a time but you still have lots, right?
There is no such thing as an insecticide that only kills cicadas. They also kill butterflies, bees, and other non-target organisms. It is important that homeowners consider the risks of these insecticides (some) compared to the benefit (none). Cicadas do not last long and pose no risk to people. Insecticides do.
The other problem with trying to manage cicadas with insecticides is that they are
generally ineffective. Especially products available to homeowners provide so little benefit that the monetary cost and risk is just not worth it. If you managed to spray a whole tree with Orthene or Sevin for instance cicadas would likely colonize it again within hours or days.
Cicadas cause damage to trees when they lay eggs in twigs. They use a knife-like ovipositor (egg inserter) to insert eggs into thin twigs. This causes slits in the branch that could be 6 inches long or more. This long scar reduces plant aesthetic value but also weakens branches. Scarred branches usually break and fall to the ground or break and remain hanging in the tree but turn brown.
Trees that are very small or that you just planted this year are at risk if they get many cicada oviposition scars. Cicadas prefer skinny branches (< 0.5 inch) so if your tree trunk is this skinny it could get damaged and this could kill your tree. Other trees will shed a few
twigs and go on about their lives. You can protect trees with mesh netting to prevent cicadas from damaging them.
If you are unhappy about having cicadas on your porch or sidewalk just sweep them off. If you apply insecticide to these trapped critters (they don’t want to be on your porch) you will end up with a dead smelly pile of cicadas that you have to sweep up anyway. In addition, as you walk across the porch and sidewalk you will get insecticide on your shoes that will be carried into your house where kids and pets play on the floor. When you take your shoes off you get insecticide on your hands. Next thing you know you are eating a sandwich.
Insecticides have a place. That is to reduce economic or aesthetic damage to plants that we eat or enjoy. Insecticide applied for cicadas won’t achieve this. So save your money and wait them out or try to enjoy them.