Cryptomeria Scale Resurfaces in Ashe County

On September 1, 2010, I make the following post: Cryptomeria Scale Found in Ashe County. If you went to any of the meetings where I spoke at the following winter, you probably heard about this new scale problem. I've not really talked much about this scale since then and with good reason -- I've not seen it again.

After making this post in 2010, the grower cut down many trees and treated the rest. I couldn't find any live scale after treatment. Since then I've been back to that field several times and scouted in close-by field and never found any more Cryptomeria scale (CS) until today.

Cryptomeria scale (Aspidiotus cryptomeriae), like elongate hemlock scale (EHS), is another introduced pest from the Orient. It affects many conifers including hemlocks and firs. It causes serious and striking yellow mottling of the foliage and premature needle drop. On the trees we examined today, most of the damage was on the south side of the tree. A few trees were heavily damaged all over with scales even on the needles of the terminal. This is one scale you really don't have to hunt for to find. If it's there, you should see it.

Damage from Cryptomeria scale.

The scale has a very different appearance to EHS. The scales, especially the small immature ones, are round, and they line up in two rows along the backside of the needle on either side of the midrib. They look like fried eggs with a yellow center. The 'white of the egg' is actually where the scale has pushed up the waxy covering of the needle. Older scales are more indistinct.

These younger scales look like they might have been killed, perhaps from a fall
insecticide treatment.

Crawlers will start to appear in another month or so.

The life cycle of CS is similar to EHS. It has two generations per year and is most active in the summer months. It seems to spread very quickly and cause damage very quickly. However, it is much easier to control than EHS.

The scale is spread through crawlers and on infested plant material. This scale was found in three adjacent fields owned by different growers. Next week, we hope to scout other farms in the area to see how far the scale has spread.

Typically when I've found CS, I've also seen the twice-stabbed lady beetle. We didn't find any today. Perhaps it's still too early in the year for this helpful predator.

The grower in 2010 treated in early September and got excellent control. We didn't see any crawlers today, and so it's probably a bit too early to treat -- especially since we are having such a cold, wet spring that's keeping everything from getting active. But we'll definitely be following control from any grower treatments and pass results on.

Twig Aphid Hatch -- Spring Pests

Twig aphids. Looked at twig aphid hatch again today. I found just over 90% of the eggs hatched (it worked out to 93%) and there were a couple of aphids that had molted. However, when Jerry Moody and I were doing beats on trees, we were still finding that they were hard to find. So if you do start scouting for twig aphids in the next few days, if you find any at all, you should probably treat in go-to-market trees.

Aphids should all be hatched out in the next few days.

Woollies. Last week we found that only a few balsam woolly adelgid eggs have been lain. This week there were whole lot more. The adults still haven't produced much wool.

Spider mites. I found my first spider mites crawling around today. Many are encysted. That means that they are molting from an immature to more mature state. When they do this, they look like they are dead. They don't move, but they are in fact alive. They are just molting and it takes awhile.

The next couple of days are supposed to be wet, but after that, start scouting trees that were treated last fall to determine if you need to treat this spring for twig aphids or for mites.

Twig Aphid Hatch

I collected shoots yesterday and examined them today. Hatch in the field I'm monitoring was at around 30%. I only saw first instar aphids -- these are the ones that have first hatched out of the egg and have not yet molted. It will be probably the last full week of April before all the twig aphids have hatched out. My advice would be to wait until late next week before scouting for twig aphids to access whether or not to treat this spring. However if you know you have to spray this spring, insecticide sprays will work any time.

Issues with Bees

The Jefferson Post printed the following article today, "Beekeepers report unprecedented losses." It just so happened that I spent today with Brad Edwards and Travis Birdsell working in our beehive at Omni farms! We've had the hive set up there since June of last year. All three of us were impressed with how strong that hive is. The following photos were taken today (April 8, 2013).

The bees bringing in pollen from maples. Photo: Travis Birdsell

We had to put up a mouse guard. Mice damaged about 5 of the frames which we
will probably have to replace.

Lots of bees when we opened the box. Photo: Travis Birdsell

It's all about making babies. The capped cells have bees that will soon emerge.
Photo: Travis Birdsell.

In many ways, Fraser fir Christmas tree production in western North Carolina helps both honey bees and native bees. Growers leave ground covers that bloom. This provides forage for pollinators as well as bringing in predators which help reduce Christmas tree pests. But this also brings an added responsibility to the grower to protect honey bees if they are actively visiting ground covers when an insecticide treatment is necessary. For ways to protect honey bees see Fraser Fir Pest Control Portal: Tips for Keeping Bees Safe.

The causes of beehive losses are complex. A good website which reviews the multiple causes is the USDA website called Honey Bees and Colony Collapse Disorder.

Keep looking for more information on this project as we are putting bees out in tree fields in Alleghany and Avery.

There's a lot of people to thank with this project including Wiley Gimlin and Omni farm for hosting our bees; Shelley Felder with the Honey Hole in West Jefferson for her technical advice about beekeeping; the NCCTA for grant support; all the extension folks -- Brad Edwards, Travis Birdsell, Jerry Moody, Meghan Baker, Jeff Owen and Jeff Vance for their assistance with this project; and Logan Williams who was key in identifying native bees collected last year. Information about the pollinator study can be found at The Pollinator Study.

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.

Protecting Pollinators and Groundcovers Continued

On March 20, I posted pictures of a field with lots of purple deadnettle following applications with suppressive rates of either Roundup, Stinger or Goal. The purpose was to stop the deadnettle from blooming so bees wouldn't be attracted to it, but still maintain a healthy living groundcover. At that time -- only 5 days after application -- only the Goal had had much effect. Today it's been 19 days since the applications made on March 15 and things have changed quite a bit.

The Stinger still isn't working at all. The following photo shows the purple deadnettle still growing well.

The Stinger didn't affect the purple deadnettle which is still blooming.

The Goal has worked too well. There are several areas where the ground has been bared. The clover has been hurt pretty bad in some spots, though I suspect it will regrow. Chickweed is filling in some spots.

White clover hit by suppressive rate of Goal.

The suppressive rate of Goal seemed to have worked a bit too well.

The Roundup now looks the best. The purple deadnettle has been stunted and yellowed, and the flowers have been stopped. 

Close-up of purple deadnettle stunted with a suppressive rate of Roundup with no flowers.

If you need a quick knockdown of weeds, Goal will do the job. But if you have more time, Roundup appears to be the better choice at least in this instance.

Protecting Pollinators & Groundcovers

Field site in Ashe County

If you follow NCSU Christmas Trees on Facebook, you saw that Jeff Owen, Brad Edwards and I treated some groundcovers -- mainly purple deadnettle -- with either Roundup, Stinger or Goal last Friday.

Why is this important? After all, the groundcovers are just now starting to grow. Typically, growers wait until late April or into May before doing any type of herbicide application. These little purple deadnettles certainly aren't impacting tree growth. When the weather gets warm, they die back naturally.

The goal of these treatments is to burn back the flowers so that bees won't be in the trees.  On warm days, bees have been in this particular field  for the past month. If the grower needed to treat with an insecticide and had to spray during the day with a high pressure sprayer, bees in the area would be at risk.

Early spring is a tough time for bees. The population of a bee hive fluctuates through the year according to the season and resources. The number of worker bees declines at the first of the year, reaching the lowest number in February/March. This is the time of the year the queen is starting to lay eggs when there are fewest bees to feed and take care of the young. A queen may produce 1,500 bees daily. Honey and pollen resources have been depleted and there are few places for bees to forage. They work red maple when it's blooming which provide both pollen and nectar. In tree fields, purple deadnettle and wild mustard bloom early and bees will be foraging in the trees.

The hope is that by using a suppressive rate of a herbicide over the top of the trees the flowers will be burned back, but the good groundcovers -- especially the clover -- won't be killed out. We tried 3 commonly used herbicides at the typical suppressive rates to determine if they would knock back the purple deadnettle and how long flowering would be suppressed.

Of course it's too early to tell completely, but I went back today to see if any materials had made a difference. It's been five days after treatment.

The only treatment that worked so far was the Goal at 13 ounces per acre. The purple deadnettle had been burned back and there were few to no flowers. So this appears to be a quick way to clean up a field of flowers. Of course, Jeff reminded me that this would only work up until the time the trees break bud. After that the Goal will burn the new growth as well.

Purple deadnettle after treatment with Goal.

The Roundup was starting to have some effect, but there were still quite a few flowers. We'll check back next week to see if it's working any better.

Purple deadnettle after suppresive rates of Roundup.

The Stinger hadn't worked at all yet on the purple deadnettle. It looked like the check. It appeared that the deadnettle had grown since Friday in these rows.

Purple deadnettle after suppresive rates of Stinger.

We'll be trying these and other materials on other spring groundcovers and other weather conditions, as well as following how long it takes for the groundcovers at this site to green back up. But it looks like Goal at suppressive rates will burn back some flowers.

Bees Already?!?

Brad Edwards and I were looking in a field treated with Safari last July to look at scale control. Long story short, the Safari worked well. I'd estimate 99% control. But what really caught our attention was what was going on under the trees. There was an almost continuous carpet of purple deadnettle that was starting to bloom. And it was full of bees! Most had pollen sacs full of red pollen.

This field was at just under 3,000 feet in elevation and southern exposure. The high was only 51 ^oF in Jefferson today. They say bees don't get out and start working until it's 55 ^oF. Obviously the bees don't read too well.

In any case, if you need to apply an insecticide, it's important to look and see if bees are in your trees. Pick a warm day at mid-day and look for bees. If you can spray at night, you should be OK. But if you have to spray in the day, clean up the field of flowers by using Roundup at suppression rates a week or so before treatment. Know if you have bee hives close by, and if you do, tell the bee keeper what you plan on doing. They may want to shut up the hive while you are spraying so the bees aren't exposed.

For more information about how to protect bees in trees see: FRASER FIR PEST CONTROL PORTAL: Tips for Keeping Bees Safe.