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