Jun 24, 2012 – Pine Needle Damage
QUESTION:
I got a call from a client who is having pine tree problems. The pines have a little worm eating the inside 'tips' of the pines. Here in New Mexico I thnk we call them tip moth but I could be mistaken. I have never dealt with a problem like this one before and asked a friend in the pest control industry what to do. He said to spray the pines with Talstar P. Is this correct advice? He also mentioned a "second flight" and timing them right. He also said I might need to use a 'systemic' product such as Cygon or merit? Any advice would be very helpful.
ANSWER:
You could well be correct that these are tip moth larvae feeding on those pine needles, and a number of species of these moths in the genus Rhyacionia occur in the western states. Some of these have only a single generation per year, but because of the various species as well as some other pine tip moths in other genera it is possible that you could see the adult moths present at different times of the year. In the most common species the fully grown larvae creates a silken cocoon on the trunk of the tree just at or below the soil surface, and then pupates here and spends the winter in the pupa stage. The adult moths emerge with warm weather in the spring and begin laying eggs on the fresh shoots of the pines in April and May, and larvae may be feeding on the needles for the next few months.
View past Ask Mr. Pest Control questions.
I got a call from a client who is having pine tree problems. The pines have a little worm eating the inside 'tips' of the pines. Here in New Mexico I thnk we call them tip moth but I could be mistaken. I have never dealt with a problem like this one before and asked a friend in the pest control industry what to do. He said to spray the pines with Talstar P. Is this correct advice? He also mentioned a "second flight" and timing them right. He also said I might need to use a 'systemic' product such as Cygon or merit? Any advice would be very helpful.
ANSWER:
You could well be correct that these are tip moth larvae feeding on those pine needles, and a number of species of these moths in the genus Rhyacionia occur in the western states. Some of these have only a single generation per year, but because of the various species as well as some other pine tip moths in other genera it is possible that you could see the adult moths present at different times of the year. In the most common species the fully grown larvae creates a silken cocoon on the trunk of the tree just at or below the soil surface, and then pupates here and spends the winter in the pupa stage. The adult moths emerge with warm weather in the spring and begin laying eggs on the fresh shoots of the pines in April and May, and larvae may be feeding on the needles for the next few months.
A species in a different genus, Dioryctria, may find adult moths ovipositing in midsummer rather than early spring, and this could be that "second flight" you mention. However, the larvae emerge from these eggs and immediately create a cocoon for the winter, resuming their feeding in early spring along with the other kinds of tip moths. The feeding from all of these moths can result in die-back of the growing tips of the pines, with dead needles and distorted tissues resulting. However, rarely does this cause any serious damage to the trees, but it does cause brown areas that may be unacceptable and overall can reduce the healthy growth of the tree.
In general you want to apply insecticides for the control of these moths as soon as the new growth is appearing on the trees, timing the application for the first feeding of the larvae in the spring. At this point a contact insecticide such as bifenthrin (Talstar and others) can be very effective, and the residual of that active ingredient may be several weeks, depending on the weather. Once the larvae have made their way into the needles or the other tissues a systemic product may be more effective, as these will enter the tissue of the plant and be consumed by the feeding larva. I don't know if you will still find Cygon (dimethoate) available, but Orthene (acephate) definitely is and it is another locally systemic product. Systemics also may have a longer residual as they are within the plant tissue and not as exposed to weather that may degrade other products.
Merit is another systemic and one that can be applied to the soil as a highly effective material taken up through the roots and moved into the foliage. It is specifically labeled for pine tip moth larvae and should be a good choice. For other foliar insect pests a single application to the soil may be effective for the entire season, but you would need to get the material in the soil around the base of the tree fairly early and well in advance of the hatching of the eggs. It takes a little while for the active ingredient to move up the tree and into the foliage where it can then be consumed by the larvae. For hardwood trees this may take several weeks, but for softwoods (pines) it is faster. If you do go with Merit and the soil application be sure to carefully read the label so you apply the proper amount for the size of the tree. The advantage of a soil-applied product like Merit is that it is then specific to the insects that are actually feeding on the tree.
Because of that second species that lays its eggs in midsummer it may be necessary to do a second treatment that is timed for the emergence of these larvae, and careful observation of the trees can tell you when new larvae may be appearing. If you can capture some of the adult moths you also can get the ID'd and will know better which species you have and what the timing is for their eggs to hatch.
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