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.

Rust Mites!!!!

I really wouldn't have thought this would be a bad year for rust mites. After all, everyone was hoping that with such a hard winter, there would be fewer pests.

Looks like we were wrong!

Rust mites are cropping up in many fields. They will probably limit the number of fields that can go without an insecticide treatment this spring. But don't just assume you have to treat. Scout first! Twig aphids are now mostly hatched and even spider mites are hatching out. So scout and determine what you need to do.

From my pest management survey, I've learned that a lot of people are depending on either a bifenthrin product such as Sniper and/or dimethoate in the spring for pest control. But with rust mites so bad, neither product is probably the best choice.

Miticides such as Envidor provide a lot longer control of rust mites and spider mites both. Though more expensive, you can treat and pretty much walk away from the situation. So if mites are the only problem and you don't have twig aphids because of a fall treatment, consider just using the Envidor without mixing another product in. That will protect your natural predators.

I also think that bifenthrin is a much better product to use in the fall for Cinara aphid and twig aphid control. Then it should have much less effect on the parasitic wasp that controls the elongate hemlock scale.

The following links will provide help for mite control, twig aphid control and/or scale control.

On other thing... is flowering mustard blooming in your trees? If so, watch out for bees when you spray! Mustard seems to be the plant that brings the most bees in when it is flowering. It is far more attractive to bees than other flowers such as clover. So take special care when mustard is blooming. The following link will help with controlling pests without hurting bees.

If you have any questions, please let me know.

Spring 2013 Pest Control

Last spring I made several posts about the effects of the warm spring on our Fraser fir pests. This spring, as you well know, is the complete opposite of last spring. Last spring we were 2-3 weeks ahead of normal. This spring we may well be 2-3 weeks behind normal.

I went out on Friday to evaluate twig aphid hatch in some untreated trees in Avery County (thanks Jerry Moody!). These trees had ice on them from the snow/sleet/freezing rain from Thursday, so it was a bit hard to evaluate twig aphids. However, the aphid eggs were very plump and ready to hatch and it appeared that a few of them had already, though I didn't see any live aphids. I estimated that about 16% of them had hatched already. Typically I see that many hatched by late March, so hatch is definitely late this year.

In most years, all twig aphids have hatched by April 15. I doubt that we have 100% twig aphid hatch by that time this year. So what does that mean for you in trying to scout and control twig aphids?

First of all, if you are scouting to determine if your fall insecticide applications have successfully controlled twig aphids this spring, you might want to wait until after the 15th. I doubt if you will see much this week in the way of twig aphids. Remember too that the aphid which hatches from the egg is the stem mother. They are all female and they reproduce without mating. At maturity they produce live young. So if you see one aphid on April 15 and your trees break bud on May 1st, that aphid has 2 weeks to mature and start reproducing. One aphid could easily turn into 15 during those two weeks. Therefore, be very cautious of scouting too early for twig aphids.

If you know you have to treat however, it's not too early to start. Any material used will last long enough to kill the aphids once they are hatched. At least one grower has already seen some rust mite activity so be sure to scout for rust mites and spider mite eggs before deciding what material to use. Also remember to protect honeybees. If the temperatures are above 50 degrees, they will be foraging in flowers.

If you are treating for twig aphids, it's a good idea to do so before cones are produced on the tree. Twig aphids will hide in the cones, protecting them from chemical spray. Once the cones have come out on trees, dimethoate is one of the few materials that will penetrate them to kill the aphids in the cones.

One word about dimethoate -- if you do have to send workers in to remove cones after treating with dimethoate during the 10 day re-entry interval, they have to wear long sleeved shirts and long pants, chemical resistant gloves and chemical resistant footwear. They don't have to wear masks.

I will keep monitoring twig aphid hatch as in years past and will keep you posted on how the spring is progressing. And if you see anything interesting when scouting let me know so I can pass that information on to others.

Hemlock Rust Mites Early This Year

The HRM is certainly enjoying this spring. This morning I found a field that had rust mite damage already on 2011 growth. Doug Hundley said he saw some rust mite damage last week. Folks, that's really early! So, be sure to scout for mites this spring.

Remember that Dimethoate will control rust mites, but not the eggs. Envidor and Sanmite control both rust mites and spider mites -- all stages. Horticultural oil and sulfur give excellent control of rust mites. Oil will give pretty good control of spider mites too if you have good coverage. Apollo and Savey do not control any stage of rust mite -- not the egg and not the mites. They are only effective against spider mites. The same is true, of course, of Talstar (bifenthrin).

And no, don't expect this cold snap to slow rust mites down. Only hot weather weather does that! And even though it's been warm lately, it still gets cold at night. Perfect rust mite weatheer.

The following are some photos I took this morning.

This shoot already has bronzing from the rust mites. Compare it's color
to the greener needles around it.

Jeff Vance easily knocked off damaged needles from the 2011 growth.

My Samsung Android amazes me sometimes. I took this photo with my phone.
You can actually see the rust mites on the needle.

A Buggy Spring!

I revisited the field I was in last week to look again at twig aphid hatch plus going to a second field today. One field is in Mitchell County along the Parkway; the other is in a high elevation site in Avery County. The following are a few observations.

• BALSAM TWIG APHIDS are at 90% hatch. The high elevation site actually had a slightly higher twig aphid hatch! If the next week continues warm, twig aphid should all be hatched out by April 1. This only happens once every 10 years or so. Usually it takes until April 15. If using Thionex (endosulfan) or Di-Syston 15 G, wait until after April 1 to treat. All other products can now be used at any time .
• SPRUCE SPIDER MITES are hatching out. They are all at the immature stage -- no adults yet. I even saw some that were encysted -- that means they were sitting very still as if dead while they molt.
• HEMLOCK RUST MITES continue to increase. At the one field in Mitchell County, I didn't see a single rust mite in my samples taken on March 13, and now about 20% of the shoots had just a few rust mites on them. That's a pretty impressive jump!

The following are some suggestions for pest control this spring:

1. Start scouting now for twig aphids and mites. Don't wait until the middle of April. If you do it now, you will have more time to do something about a mite or aphid problem.
2. Be sure you to scout a second time before bud break to make sure something hasn't become more of an issue if you aren't planning on putting out an insecticide this spring.
3. Scouting doesn't have to be a big production either. Just going to key fields and blocks, getting out of the truck and walking to half a dozen trees should tell you all you need to know.
4. Don't just expect fall pesticides to control twig aphids -- scout to make sure they have worked.
5. Be aware of the weather. If it stays pretty, those few mites and aphids this week will be at very damaging levels by bud break. What would stop this is several days in a row of wet weather or a return of winter for a few days.
6. Remember that Dimethoate will only give a knock-down of mites. If the weather stays favorable (which so far it has) those mites will come back from the eggs. However if all the spider mite eggs are hatched and they haven't yet started to lay more eggs, then a single treatment of Dimethoate should work well. This also means that Apollo and Savey, products that only work on eggs and immatures, will not need to be mixed with another miticide such as Dimethoate to work. But this will only be true for about another week. For a list of miticides and how they work see Christmas Tree Note # 29: Spruce Spider Mite on Fraser Fir. 
7. Remember to use up your Thionex before July 31 of this year. Wait until April 1 before using it if you want twig aphid control.

If you have any questions, email me at jill_sidebottom@ncsu.edu

Good luck this buggy spring!

Spring Bugs

SUMMARY: With the spring weather, many pests and predators are becoming active. Twig aphids are already starting to hatch which is earlier than most years. Rust mites are very active. Cinara aphid populations may be crashing from earlier this year with increased activity from lady bugs. Be sure to be in your trees scouting so that you'll know if you need to treat and can choose the best materials for control. For more details, see below!

Spring has sprung as they say and bugs are no exception. Today I visited two fields in Mitchell County with Jeff Vance and found a lot of activity.

Cinara aphids. In one field, we've been following a heavy incidence of Cinara aphids since the first of the year. Most of these aphids are dead already from natural causes. We saw several Harmonia lady beetles feeding on them. We also found some white sap or honeydew on some of the needles. I tasted it and it was definitely sweet. There's a lot of sooty mold too on the trunks and branches --  parting gift from these pests! Below are some photos.

Most of the aphids are dead, but there is one in the middle right hand that is still alive.

White sap or honeydew on the needles where Cinara aphids have been feeding.

Harmonia lady beetle.

I think this lady beetle is infected with a fungus.

Balsam twig aphids. The aphids have started to hatch already. They are about a week to 10 days earlier than normal. I would estimate that 25% of the eggs have hatched already. I did see a dead aphid and an egg that looked like it might be dead -- black inside. A lot of rain will be hard on the aphids and some will die. A cold snap will kill many too if we have one.

However, I am afraid that since the spring is so early and it is staying warm, that twig aphids may be bad this year. Be sure to scout in fields where you treated last fall with bifenthrin products such as Talstar to make sure that you have good enough control. The warmer it is and the longer time from egg hatch to bud break, the longer the aphids will have to mature and reproduce. This may be the year that fall twig aphid controls fail us, so be sure to keep looking!

If you are treating this spring for twig aphids, you can start treatments any time . The only exceptions are Thionex and Di-Syston. With these products you need to wait until all the twig aphids have hatched, but that may be within two weeks!

Hemlock rust mites. Another pest that really likes the early spring are hemlock rust mites. In one field I was in today, the rust mite population was almost at treatment threshold. It was at 60% incidence and one shoot had at least 8 mites per needle.

Rust mites like spring and since we are having a pretty one, they will most likely be bad. They haven't been the last few years, so don't be caught off guard. Be sure to scout fields and treat for them if necessary. What are the best materials for HRM control? Horticultural oil, Envidor, and Sanmite are three of our best products. Dimethoate knocks rust mite problems down, but they will rebound. In fields with rust mites, be careful about using synthetic pyrethroids (Asana, Astro, Talstar, Wisdom, and Sniper) as these products will make rust mites worse. They may also make elongate hemlock scales worse, so only use them when necessary in the spring, or better yet, save their use until fall.

Spruce spider mites. I saw quite a few spider mite eggs today, but no mites that are hatched out yet. I do know of some folks that have seen mites crawling. If the weather continues warm, I'm sure it won't be long until they are active.

Twice stabbed lady beetle. We also found a couple of twice stabbed lady beetles active in trees that have elongate hemlock scales. Here is a photo.

From this angle you can only see one of the red spots.
Still not a bad shot considering I was using my cell phone!

What's the take home lesson with all of this? It's time to scout, of course!! Be sure to get out in your trees over the next couple of weeks to see what's active. And pay careful attention to rust mites.

Horticultural Oil

Now is a great time to apply horticultural oil for control of Fraser fir pests. Horticultural oil is the workhorse of organic pest control of Christmas trees. But even if you aren't growing organic certified trees, it provides a good way to control most pests. It can control balsam woolly adelgid (BWA), balsam twig aphid (BTA), spruce spider mite (SSM), hemlock rust mites (HRM), and elongate hemlock scale (EHS).

Oil burn on needles

How oil works. Oil controls pests by smothering them. Therefore, you have to get complete coverage of the tree so that pests on all surfaces are coated with the oil solution. For pest control, a 2% solution of oil (that is 2 gallons in 100 gallons) is required. At this concentration, however, the tree may be damaged. Needles may turn brown and drop off the tree.

Types of oil. Not all oils are alike. To get the best pest control without foliage burn, use a highly refined horticultural oil. These are often called summer oils. Do not use a dormant oil as these will cause foliage burn. Look for oils with at least 92% unsulfonated residues on the label. But the higher, the better! It will list this value under the active ingredients.

Encapsulated oil -- a new type of oil. There is a new type of oil on the market called Saf-T-Side oil. The encapsulation process results in an oil that mixes with water with water and won't cause burn. This is more expensive than regular oil, but you will not need good agitation in the spray tank.

Applying oil. Typically a high pressure sprayer will give better coverage. If a limited number of trees are being treated, you may also use a backpack mistblower. Treat trees from opposite directions to get the best coverage. If you are controlling BWA, you have to wet the tree all the way to the trunk.

The encapsulated oil can be used with any type of sprayer. Other oils should only be used if there is good agitation in the spray tank. A paddle type agitator is better than by-pass pressure recirculating into the tank because the agitation is continuous. The oil and water can separate in the hose if you stop spraying for awhile, so if you do spray what's in the hose back into the tank to remix the solution.

Twig aphid egg killed by oil

What oils will and will not do. Horticultural oil has no residue. It only kills on contact at the time of application. Control of some pests is excellent, but control of other pests is not as good. However, if oil is used each year, pest numbers will continue to be suppressed.

A 2% solution of oil applied in mid-March will do a good job of controlling the following pests:

• All stages of HRM -- actually oil works as well as expensive miticides when controlling rust mites
• BTA eggs
• SSM eggs
• BWA crawlers, nymphs, and adults though the adults are covered with white wool and are therefore harder to wet.
• Cinara aphids

Control of the following pests is not as good. A 2% solution of oil will only suppress the following:

• BWA eggs – however, there shouldn’t be any BWA eggs present in mid-March
• BTA nymphs or adults. Therefore be sure to treat before the twig aphid eggs start to hatch
• EHS -- this is really too early in the year to get good EHS control. You can treat for this pest in the summer with oil, but problems with burning foliage increase in hot weather.

Be sure to keep scouting through the spring to make sure treatments have worked.

Mites on the Move

Finally got out in some trees yesterday, and didn't have any problems finding mites -- both rust mites and spider mites. The spider mites are just now starting to hatch out and move around. Taking a quick check on mites in your trees will help you decide what pesticides to apply this spring, or even if you can skip a treatment.

The March 10, 2010 post "Spring Insecticides for Pest Control" gives a good summary of materials you can use this spring. The following image reviews how well some of the common materials control different pests. The big X means it works really well. The smaller x means it only works somewhat and might need an added material to give really good control.

Other miticides that you might use include the following:

1. Sanmite which like Envidor controls all stages of both spruce spider mite and hemlock rust mite
2. Savey which controls the eggs and immatures of spider mites -- no activity against rust mites
3. Apollo which has the same type control as Savey
4. Floramite which should control all stages of spider mites

It's always good to rotate materials, especially with pests like mites that have multiple generations each year.

Remember that Thionex will no longer be available for sale after July 2011, and you can't use it after July 2012, so don't purchase now more than you can use.

For a listing of pesticides labeled for Christmas trees and links to the labels and MSDS sheets, view our new pesticide page. 

For information about farm and pesticide safety, go to our new safety page.

Pests Getting Started This Spring

Hasn't the weather been fun the last few weeks? Talk about a yo-yo! That's hard on us, and it's hard on bugs too. Warm weather allows them to mature and reproduce quicker and survive better. Cold and wet has the opposite effect. So what are people seeing now?

BTA

I haven't been out in the field yet, but Doug Hundley has reported seeing three instars of twig aphids. If you will recall, these aphids begin hatching from their eggs in mid to late March. They molt four times before becoming an adult which can produce more live young.  So what does that mean? What's an instar?

Remember that insects don't grow like mammals do. I have a new puppy, and every few days I think -- Gosh he seems bigger. Insects don't do that. They grow in stages since they have to shed their skin (molt) to get bigger. Different species of insects mature differently. Twig aphids have four molts so there are four instars. If Doug was seeing three different sizes of aphids, that means that the twig aphids are hatching and growing and fairly far along with their life cycle. But also remember that twig aphids hatch over a several week period. The oldest aphids he saw were probably the first ones to hatch. Usually it takes until April 15 for all the aphids to hatch out. I would think that with our periods of snow and cold which seem to come every week, that it will take that long for the twig aphids to completely hatch. However, if you are using any insecticide except for granular Di-Syston or Thionex, any materials you spray now will work fine. It will last long enough. These two work best when applied after all the eggs have hatched.

So is it best to wait later in April to early May to treat for twig aphids? Not necessarily. First of all, the longer you wait, the more you at the mercy of the weather. The other factor are cones. Cones can reduce the effectiveness of insecticide applications. The bracts on the cones protect the aphids. When the cones are very small, the aphids can't get under these bracts. So if you have a lot of cones and are spraying for twig aphids, it would be better to treat sooner than later. Otherwise you will have to remove all the cones. Of course, you'll probably do that anyway.

Dimethoate has proven effective even when the cones are more mature, so if you get caught with bigger cones, consider switching to that material.

HRM

Brad Edwards reported seeing some rust mite activity recently. The presence of rust mites in the spring may affect what pesticides you want to use. If you treated in the fall with Talstar and don't have and twig aphids this spring, you might still need to spray if you have rust mites. And if you were going to spray anyway, the presence of rust mites may make you want to add a miticide. Remember that Talstar, Apollo, and Savey don't have any activity against rust mites. They only control spider mites. Dimethoate controls rust mites but not the eggs. If this materials is used -- especially early in April -- you might have to reapply come May. Sanmite and Envidor control all stages of both rust mites and spider mites, making them worth the extra cost.

So how do you know if you controlled your twig aphids last fall or if you have rust mites? That's right. You need to scout!

End of May Explosions

Rust Mites. Bryan Davis has seen in a few fields a real upsurge of rust mites in the last few weeks. With the cooler weather, and especially cool nights, rust mites are remaining active. Some of the fields that only had a few rust mites in them a month ago are getting damage now. So if you haven't been in your trees lately and the field is prone to rust mites, it might be a good idea to check and see if rust mite numbers have exploded.

Should these fields be treated now? That should be decided on an individual case basis. The weather should be warming up soon, but as long as the nights stay cool, rust mites will continue to be active. Only treat now if mite numbers and damage truly warrant it.

Twig Aphids.  Also, there have been a few fields that weren't treated for twig aphids this spring because of fall treatments that twig aphid numbers seemed to explode in. A month ago, there weren't any twig aphids, but now there is some damage.

This spring allowed the few aphids that did survive a chance to quickly reproduce. However, with all the wet weather, the trees are growing so well that much of that needle curl will be grown out of. So it is nothing to treat for, but only to be aware of.

Role of Apollo

Several folks have been talking about treating this spring with Apollo plus Dimethoate. Apollo is a miticide with similar activity to Savey. Those Apollo plus Dimethoate should give good control of twig aphids and spider mites, but only fair control of rust mites. After all Apollo, though an ovicide, has no activity against rust mites, just as Savey doesn't.

The kicker is, there are almost no spider mites anywhere. I've worked  tree fields for several weeks, Bryan Davis has, and several other agents. Fields with spider mites are few and far between. I think I've seen a dozen spider mites eggs total in 3 weeks of scouting.

Rust mites, however, are being found frequently. A few fields have high rust mite numbers. Other just have maybe a mite per shoot. (Remember that the treatment threshold is 80% incidence and at least 8 mites per needle).

The mix of Apollo + Dimethoate will knock rust mites down (due to the Dimethoate), but since it is so early in the season, the mites may rebound. That is why in a situation where rust mites are plentiful now, Envidor is the better choice. It controls both spider mites and rust mites. Envidor plus Dimethoate should give excellent and full season control of twig aphids, rust mites and spider mites.

Scouting will determine which blocks should have the Envidor added, and which don't, as rust mites are not a problem in every farm or even on every block on a farm. Don't assume that just because you used either Asana or Talstar last fall that rust mites are a problem. They aren't. You don't know until you go out and look.

And scouting doesn't have to take a lot of time. When I go out with the county agent or technician, it always takes longer because we're talking about control options, showing the grower different pests and the like. But if I was just going out there to scout, it wouldn't take me long at all.

Envidor is only labeled to be applied once per year (as is Savey and I think Apollo as well). This is to reduce the likelihood of resistance. But chances are, spider mites won't develop and become a problem if you have good ground covers. Even during droughty years, we've seen very few farms with bad spider mites in recent years. Once again, a quick scout through should be able to identify problem sites.

So scout. Then chose what you need based on those scouting results.

End of March Assessments

I've had the opportunity to walk through several Christmas tree fields the last couple of weeks. Here are some of my observations.

BALSAM TWIG APHIDS: I'm still not seeing many fields that have high twig aphid numbers. I finally found a couple that did, but mostly there aren't many aphid eggs. Bryan and I found our first live twig aphid on March 30! It was tiny -- just a fist instar. The weather during April will determine how bad twig aphids end up being. Now we're having warm, dry weather which will allow the aphids to quickly hatch, mature, and start to reproduce -- laying live young. If this kind of weather keeps up, those few aphid eggs will turn into plenty of aphids to curl needles by bud break.

We were in one field that had been treated with Talstar in the fall, that actually had a dead aphid sticking out of the aphid egg. But it's still a bit early to be evaluating how these fall aphid treatments are working. Wait until April 15, and then it should be easy to beat aphids out of trees if they are present.

However, if you didn't treat in the fall, and you need to control twig aphids, don't wait until the 15th unless you are using either Di-Syston or Thionex. All other materials including Asana, Talstar (Wisdom), and Dimethoate can be applied now.

BALSAM WOOLLY ADELGID: I visited another field yesterday where several trees were showing symptoms of woollies (flat tops, swollen buds, stiff trunks), but it was extremely hard to find any live woolly on the trees. What we did find were on the buds, and we had to look at lots of buds before we found them. These trees had been completely untreated in 2009. Therefore, I think we're seeing quite a bit of winter kill of BWA, but don't assume they are all killed out. Fields with symptoms of woollies should still be treated for them.

SPRUCE SPIDER MITES: I have yet to find a field with more than just a few spider mite eggs this spring. I'm sure they are out there, but for now, I don't think there are many growers that will have to worry about this pest.

HEMLOCK RUST MITES: Rust mites are really active this spring -- much more so than in the last couple of years. We walked through several fields last week that had been treated in July or August with Dimethoate + Asana to control elongate hemlock scale. This is a combination that should create rust mite problems the following spring, but of the four fields we visited, only one had rust mites. The other fields had virtually no mites.

We walked through another farm this week that had been treated with Talstar in October. It was a very large farm that rambled up and over a ridge, dropping down to the river. On the ridge top, the rust mites were nearing treatment threshold. In other areas of the farm, there weren't any.

So what's a grower to do??? SCOUT!!!! You can find the blocks that need rust mite controls and target only those for treatment. It doesn't take a lot of time to scout. A field of several acres can be evaluated in just 30 minutes. That's worth knowing where you need and don't need rust mite control.

Envidor will provide longer lasting control than just dimethoate. After all, it's a long time until summer. Spring's barely started.

Rust Mites & Twig Aphids

Just wanted to let folks know that I was in a field yesterday that had quite a few rust mites. It was up to our treatment threshold of 80% incidence and at least 8 mites per needle on one shoot. The most I saw was 25 mites on a single needle. So, it's not too early to get out there and look for rust mites.

I haven't seen my first twig aphid hatched out yet, but I'm sure they have started to hatch. Really, there aren't many fields that have much twig aphid in them. You might have to pull of 10 to 15 shoots before you find an aphid egg. Don't be fooled, though. That slight number is still enough to cause damage if we get a warm, dry spring. Of course, we haven't so far, so we might do well with twig aphids this year.

Spring Insecticides for Pest Control

The weather so far this year has put many people behind already. Many growers treated last fall with insecticides and are hoping to get twig aphid control this spring from those fall sprays. In fact, in talking with county agents, we estimated that at least 4,000 acres of Fraser fir Christmas trees were treated in the fall and will hopefully skip a twig aphid treatment.

But what options do growers have that didn't treat in the fall? I'll try and list them all below. If anyone has any other's they'd like to share, email me and I'll add them. As I go through different materials, I'll be using abbreviations for pests with BWA=balsam woolly adelgid, BTA=balsam twig aphid, SSM=spruce spider mite, HRM=hemlock rust mite, and EHS=elongate hemlock scale.

The first consideration is do you even need to treat for twig aphids? If you aren't cutting out of the trees this year or next, you don't need to control BTA. You should walk through your trees to make sure mites aren't a problem, but you can probably skip treatments.

A second consider is what have you used in the past for insect control. It's important to rotate materials from different chemical families. In other words, products like Asana and Talstar are both synthetic pyrethroids and so have similar modes of action. Think about what you used in past years, and try to use other products this year. For a complete listing of all the chemical families, go to the IRAC Mode of Action Classification.

Another consideration is that it doesn't all have to be done in the spring. You can get control of pests in the summer and fall when you have more time and can pick better weather conditions. At the end of this post, I have some possibilities for when to treat if you have all the major pests.

And just a few more words of wisdom: Remember that all pesticides are dangerous to something -- whether the bees in your trees, or the stream insects below your field, or the man putting it out -- so read and follow the label. Labels can change every year, so be sure to read them each spring. Also, be considerate of your neighbors. Remember that getting good coverage is just as important as what material(s) you choose to use. Also remember that if the wind is blowing, or if it rains before the spray has dried, you are wasting your time and money. Be sure to scout after using any of these products to make sure they have worked.

Anyway, here is a list of products, their rates, different mixes and what they will control.

1. Horticultural oil. Use a highly refined oil -- 92% unsulfonated residues or better -- at the full 2% solution -- that is 2 gallons in 100 gallons of water. When applied in March with a high pressure sprayer, it will control BTA and HRM very well, and will help reduce SSM, BWA, and even EHS. Be sure to get good agitation so the oil and water don't separate. We're going to be looking closer at Saf-T-Side oil which won't separate in water to see how well that works.
2. Asana. Can be used anytime from February through bud break to control BTA (5 oz/100 gallons) and BWA (10 oz/100 gallons). Add a miticide if mites are present. Will also knockdown EHS. However, there is also a potential to create problems with HRM and SSM when using Asana -- even the following spring. If BWA control can wait until fall, rust mite problems can be avoided when using this product. 
3. Dimethoate. Use at full rate of 24 oz/acre. From last week of March through bud break will control BTA and knock-down EHS, HRM and SSM.
4. Dimethaote + Savey -- BTA plus SSM control (the Savey controls the mite eggs). Also Apollo can be used in this manner. Still will only knockdown EHS and HRM.
5. Di-Syston 15 G -- There might be some folks who are still using this. It will control BTA and SSM and possibly a brief knockdown HRM. Be sure to apply when there is no wind and scout after treatment to make sure it worked.
6. Talstar. Use at full rate of 40 oz/acre. Will give BTA and BWA control from February through bud break. Should also give control of SSM. (Though Talstar doesn't have any activity against mite eggs, it should last long enough to kill the mites that hatch from the eggs). Doesn't control HRM or EHS well.
7. Talstar + Dimethoate -- BTA, BWA, SSM and knockdown of HRM and EHS.
8. Thionex. Use at full rate of 2/3rds of a quart (about 21 ounces) for BWA control. Wait until mid April through bud break to get BTA control as well. (It just seems that BTA control is more reliable with Thionex if you wait until all the aphids have hatched out). Add a miticide if mites are present. Has no activity against EHS.
9. Thionex + Dimethoate -- BTA, BWA control and EHS, SSM and HRM knockdown. Some folks have been using this mix without scouting first, thinking that it will control about every pest. But control of mites and scales will only be fair.
10. Envidor. Use at 18 oz/acre for HRM and 25 oz/acre for SSM control. Therefore, if you add Envidor to any of these products listed above, you will also control these mites. Will it keep the mites from developing later in the year or next year? Probably not. I would prefer seeing people keep on scouting and apply when needed -- not as a preventative.
11. Dimethoate + Asana -- Use dimethoate at rate of 16 oz/100 gallons and Asana at the highest rate of 10 oz/100 gallons. Will control BTA, BWA, EHS and knockdown SSM and HRM. Wait as close to bud break as possible to get the most out of EHS control.This mix would give better control of EHS in summer.
12. Dimethoate + Prev-Am Use Prev-Am at 0.4% solution (50 oz/100 gallons). Will control BTA, EHS and knock-down of SSM and HRM. Prev-Am has burned trees at higher rates, so be careful, but this mix sure smells better than straight dimethoate!
13. Lorsban -- will control BTA and knockdown SSM and HRM (?). Will also control BWA in March -- but not once woollies start laying eggs. Will control EHS??? We're still looking at this, but it did a great job last October. We've seen some issues with Lorsban burning foliage, so be careful.

So, what would I use if I had everything -- BWA, BTA, SSM, HRM, and EHS? I would probably either use Asana + Dimethoate and continue scouting for the mites to see it they rebound, treating with Envidor if they do, or go ahead and use Asana + Dimethoate + Envidor (which would be rather pricey). Or, I might wait to control my BWA and EHS in the summer with Dimethoate + Asana, and just use dimethoate in the spring -- and scout for mites later on. If you wait until August or September, you should pick up BTA control for the following year. Or I might use oil in March every year to control all these pests.