Time to Scout -- Time to Treat

Twig aphid numbers. If you have twig aphids in your Fraser fir Christmas trees in western NC, you should be able to find them now. They are still quite small, but they have all hatched out. So if you treated your fields last fall for Cinara aphids, you might be able to skip treating for twig aphids this spring. But the only way you'll know for sure is to scout.

The aphids go through several molts before becoming adults. At maturity, this first stage is called the stem mother and she will produce live young aphids which quickly build up the numbers. That's why it's so hard to judge how much damage there will be by the twig aphids. It's a function of how many aphids there are right at bud break, and how quickly the new growth of the tree elongates and becomes resistant to damage. This is all modified by the weather on a daily basis.

To scout, get your plates out and start beating foliage to assess twig aphid numbers. Be sure to use a hand lens as the aphids can be quite small. It's best to wait until the foliage is dry (a challenge for this week!) but if you're good at scouting and don't mind getting wet, you can find them about any time. If you're not sure how to scout, contact your county extension agent.

If you see more than an aphid or two in a block and the trees will be marketed this year, go ahead and plan on treating this spring.

Christy Bredenkamp beating foliage to scout for twig aphids.

Look with a hand lens as the aphids are often quite small.
These tiny aphids will be having babies in just a week or two.

There are at least 6 aphids pictured here along with round balls of honey dew. When scanning a shoot
with a hand lens, you can often spot the aphids by the ball of honey dew.

Rust mites. There are several fields where rust mites are a problem this spring. Mites aren't in every field. The best way to assess rust mites is to pull some of the smaller shoots of growth and scan the back side of the needles for the tiny mites. If you don't need to treat for twig aphids but mites are a problem, you might have to treat anyway. Mark infested trees and go back to them to see if the numbers are building and treatment is necessary.

Choose shoots like this to look for rust mites.
You can also look for twig aphids, spider mites, and scales when scouting shoots.

Flowers & bees. Purple deadnettle must really like the weather we've been having. It is blooming everywhere and on sunny days, it is bringing in the honey bees and bumble bees. Wild mustard is also blooming now in fields and it is even more attractive to bees. So if you have these blooming in your field, either spray at night, or hit the ground covers with a low rate of Roundup or other herbicide to knock back the flowers before spraying.

Purple dead nettle

Bud break. The trees are just starting to move, so we should be 2 to 3 weeks away from bud break.

The Spring Rush. There's a lot to do in the spring. This week looks like it will continue to be wet and not good weather for spraying at all. When it comes to spraying fields before bud break, it's natural to want to just get it done and ignore the weather, but many times insecticide treatments fail because of too much wind during treatment or rain right after treatment. So prioritize your fields, pick your days, and pay attention to changing weather conditions. It's better to leave a field untreated and let the predators clean up twig aphids than to waste your money and pesticides and cause problems with your neighbors by spraying when it's too windy.

Useful links. Here are some links to more information. Remember our main website has changed the web address to christmastrees.ces.ncsu.edu

• Controls Based on Treatment Window -- Spring: April through Bud Break
• Balsam Twig Aphid on Fraser Fir
• Focus on Aphid Control
• Rust Mites on Christmas Trees
• Focus on Mite Control
• Tips for Keeping Bees Safe
• Weather Conditions When Spraying

2015 Scouting Project & Early Pest Observations

Brad Edwards looking for twig aphid eggs

Because of the issues that people had in 2014 with twig aphids (BTA), and the continued issues with elongate hemlock scale (EHS), this year I'm doing an intensive scouting project. I plan on visiting 2-4 farms in the main Christmas tree counties every two weeks through the spring and summer to observe how well natural predators are working at pest control. I've been visiting potential sites the last couple of weeks to set up the project and there are a few things I've already noticed.

Twig Aphids:  I'm finding that most fields have high numbers of BTA eggs in them. Actually the fields with the lowest eggs counts are the ones that have the least amounts of pesticides last spring -- such as organically grown trees or abandoned fields. That's because the natural predators ate the aphids before they could lay any eggs. That's one thing I hope to observe this year -- what predators are most important and how early in the spring they show up.

Another thing we've observed already is that BTA eggs started to hatch the 2nd week in March which is actually earlier than normal. Typically it takes about 3 weeks for all the eggs to hatch. This may well mean that we have an early overall hatch this year. (I'll keep you posted).

For scouting, that means that by around April 10, you should be able to go out into the field and beat the foliage over a plate to see if aphids are present or not. If you sprayed last fall with a synthetic pyrethroid, this would be the time to check to see if you can get away without treating this spring. Don't look before that time as all the eggs haven't hatched yet. And also evaluate other pests such as rust mites, which leads me to the next observation.

Rust Mites: There are already a few fields with active rust mites in them. It might be a good idea to go ahead and check fields where rust mites have been a problem in the past, or fields treated last spring with a pyrethroid, to see if they are making an appearance. If rust mites are a problem, you might need to treat this spring even if twig aphids have been controlled. Also keep an eye on the weather. Rust mites love long springs. I have a feeling that this year there will be good weather for them to be a factor in many fields.

Keep Posted and Thanks! In any case, thanks to the growers who are letting me work in their fields and to the county extension agents who are helping me to make these evaluations. I plan on posting observations here so stay tuned! This work is funded in part by the North Carolina Christmas Tree Association.

Changes to Safari Label

Honey bee in white clover

Many of you are no doubt following the news about bee decline in the US and worldwide. Due to concerns about neonicotinoids in particular, the US EPA is making changes to the labels of these products.

Many growers are using Safari (dinotefuran), a neonicotinoid, for the control of elongate hemlock scale in Fraser fir Christmas trees. This product has proven to be the most effective at controlling scale in western North Carolina. Safari can be sprayed on the foliage or it can be applied as a trunk application. Both have proven effective.

The previous label of Safari indicated that plants shouldn't be sprayed if bees are visiting the treated area. This allowed the product to be applied of an evening or at night when bees weren't active.

The new Safari label which came out in 2014, is far more restrictive. The label now states that this product is "toxic to bees exposed to residue for more than 38 hours following treatment. Do not apply this product to blooming, pollen-shedding or nectar-producing parts of plants if bees may forage on the plants during this time period." The label also indicates it can't be applied "while bees are foraging" or "to plants that are flowering. Only apply after all flower petals have fallen off."

In other words -- no flowers period.

So what's a grower to do? Ground covers in Christmas trees are an integral part of integrated pest management. Besides controlling erosion and making the soil cooler so tree roots are closer to the surface, ground covers keep problem weeds from coming into a field and they are habitat for natural predators such as lady beetles, hover flies and lacewings.

In 2013, Jeff Owen conducted several demonstrations to find ways to keep good ground covers while getting rid of flowers and therefore bees. What he found was that our typical chemical mowing with Roundup will burn back flowers in ground covers including white clover within one to two weeks depending on the weather. Therefore, it's important when applying Safari, to time applications after a herbicide treatment. It's also important to scout before making an application to see if bees are visiting the area any further.

Protecting bees from pesticides is important, but flowering ground covers are also important to provide forage for bees as well for natural predators as well. With a little forethought, Fraser fir Christmas tree growers can create a win-win situation for themselves and pollinators.