- 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:
- 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.
- 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.
- 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.
- Don't just expect fall pesticides to control twig aphids -- scout to make sure they have worked.
- 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.
- 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.
- 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 firstname.lastname@example.org
Good luck this buggy spring!