Indiana Department of Natural Resources sent this bulletin at 01/25/2024 08:25 AM EST
Weekly Review for January 25, 2024
This informal report by the Division of Entomology & Plant Pathology is a commentary on insects, diseases, and curiosities division staff encounter on a week-to-week basis. Comments and questions about this report are welcome and can be sent to your respective Inspector.
A while back, the USDA came out with new plant cold hardiness maps. With this revision, about half of the United States moved to the next half zone warmer while the rest of the country stayed the same. Personally, in Rochester we went from Zone 5b to 6a. But before you start thinking about growing palm trees in Indiana, there are a few things to consider about this new map.
The new version used almost doubled the number of weather stations and more sophisticated mapping tools. While some areas saw increases in temperature, the new data also led to a certain amount of zone boundary changes and “error correction” from the 2012 map.
This map only considers minimum cold temperatures. The survivability of any particular plant species is dependent on a myriad of factors including duration of those temperatures as well as precipitation, humidity, soils, and sun exposure (intensity and duration).
The number on the map is not the end of the story. Microclimates can lead to large temperature variations on a single property. Sun exposure, wind protection, thermal mass (buildings, sidewalks, stonework), and elevation changes can all lead to significant temperature variation. I have a friend who regularly grows Zone 8 plants on her Zone 6a property through careful site selection and protective mulching.
Proper greenhouse sanitation starts the growing season off right. It reduces active and dormant pathogens. That can reduce the in-season cost of managing those pathogens and other pests as well as improve your plant quality. Southern Indiana greenhouses may already be growing starts but it’s not too late to sanitize.
Consider:
Discarding used soil or potting media
Destroying leftover plants, prunings, and culled plants, especially heavily infected plants or those with untreatable diseases
Clearing excess soil and plant debris from floors and benches
Covering dirt walkways with clean gravel, concrete, or landscape cloth
Disinfecting pots, benches, floors, waste receptacles, and tools
Cleaning or installing sanitizer footbaths
Check out these Extension publications for more information:
There has not been much in the news lately about the yellow-legged hornet since it was first found in Georgia a couple months back. But there have now been five nests found and destroyed. The hornets made a small blip in the news cycle when on Nov. 9 a hornet was trapped in Jasper County, South Carolina, which is just north over the border from Savannah, Georgia.
This catch shows there is still at least one more active nest which has yet to be found. With more than five active nests being found so far this season it is also probable that this is at least the hornets’ second season and they are actively reproducing. I’m still hopefully that this is going to be something we can eradicate. Below is a map of the trapping which has been done to date. If you would like to receive direct updates, you can sign up for the Yellow-Legged Ledger which is put out by the Georgia Department of Agriculture.
As a reminder, the yellow-legged hornet is a different species from the larger northern giant hornet (aka “murder hornet”) that has been found on the West Coast. Both of these species could become a threat to honey production and native pollinators if allowed to establish in the United States.
