Thanks to a knowledgeable reader of this blog, we now know that the insects attacking my chestnuts are chestnut weevils. They may be either the Larger or the Lesser Chestnut Weevils, Curculio sayi and Curculio caryatrypes, respectively. These members of the Beetle Order lay their eggs on the ripening chestnut burrs just as they are about to open, so sometime in late September. The eggs hatch soon after, the larvae bore into the ripe chestnuts, and they grow to maturity inside the nuts in just a few weeks.
With this knowledge, we can now spray against these pest in a more timely manner. My sincere thanks to Tim Eck.
We have had unseasonable weather over most of the U.S.A. this winter, and to some extent over Europe as well. Most commentary on this phenomenon has blamed La Niña, in which the waters of the central Pacific Ocean are cooler than usual. Of interest was a piece in 80 beats last week that blamed the Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO). It appeared on January 12th, so scroll down to that entry, if you look in 80 beats.
My take on it is that global climate change, caused by the extra energy that is being trapped in the atmosphere and oceans, is simply driving weather farther from equilibrium over a background of generally higher temperatures year-round. This should show up in more extreme weather, whether in La Niña, the Arctic Oscillation, or the North Atlantic Oscillation.
On January 10th, there was also a piece in 80 beats suggesting that global warming may be delaying the next Ice Age. A small Silver Lining to a scary Dark Cloud?
Last year, we had a devastating plague of mealy bugs in the big greenhouse. I'm not sure which species this outbreak was, and that is not critical in any case. In the autumn, we threw out all the plants that were too sick to recover, and many of those that had the heaviest infestations with the bugs. Then we started spraying.
At this point, there are far fewer plants in that greenhouse. Most of those remaining have no signs of living mealy bugs, but here and there I still find a few plants with bug sign; so I'm still spraying occasionally.
Having been fighting mealy bugs for years using imidacloprid, I am beginning to worry that my strain of mealy bugs is becoming immune to this insecticide. As a result, we now treat with a second insecticide mixed with the imidacloprid. This is generally a pyrethroid type, and we currently are using bifenthrin as the second component. It is supposed to be an effective contact insecticide, and to have residual action. This technique appears to be working, as we have to really search to find any living mealy bugs now.
If you get an infestation of mealy bugs that you can't control by hand-killing them (e.g., with a Q-tip dipped in rubbing alcohol), be sure to use some sort of combination of insecticides. Always using just one insecticide can lead to development of resistant strains. Consult your local Agricultural Extension agent for specific instructions, and always follow label directions.
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Good gardening, from here in central Indiana
Look up technical terms in the Glossary of Plant Biology