It is the middle of February and I have bearded iris blooming in my yard. And it has been blooming for two weeks. All around Augusta, we are getting a spring show in the dead of winter. I should be enjoying it, but it is somehow making me nervous. I keep thinking it is going to get cold, yet the 10-day forecast says more springtime in Augusta. In Georgia’s Gwinnett County, celebrity whistle pig General Beauregard Lee made it official on Feb. 2 that spring is here early when he didn’t see his shadow. What is that going to mean for plant health and insect quantities?
Our biggest concern for the scare of cold weather is for potential freezes in flowers and developing fruit on fruiting trees. Our last frost for winter for the past 12 years has been no earlier than March 8 and as late as April 16. That spells trouble for some of our plants. When the trees start blooming, next comes the fruit. This is part of the cycle that is critical for a crop. When a cold snap hits 28 degrees, all this blooming and fruiting comes to a halt and we won’t have peaches.
So many times I have seen the saucer magnolias (Magnolia x soulangeana) put on a show with their purple and white blossoms to only get decimated by a hard freeze. This year has been a special year for this Chinese hybrid magnolia. Nurserymen love when this plant does well because they sell them for the show they put on in the late winter.
In our landscapes, our mophead hydrangeas (Hydrangea macrophylla) start putting out leaves when we have periods of warm weather and they are very susceptible to freezes. They will put leaves back on if they get knocked back by frost, but don’t expect the plant to look as nice for our Masters Tournament guests.
On the flip side, we have some fruiting plants like blueberries and apples that need a certain amount of chill hours to bloom and produce fruit. A chill hour is the number of hours from fall thru spring the temperature dips below 45 degrees. As of Feb. 13, we have had 425 fewer chill hours compared to the average chill hours of the past seven years at the same time. In other words, it has cumulatively been a warm winter.
Just as our winter weeds really start taking off, get ready for warm-season weeds. Soil temperature is on the rise and that means warm-season weed seeds will start germinating soon. My normal recommendation for pre-emergence for warm-season weeds is late February and into March. We need to get that pre-emergence out now or the weeds are going to be rough this year.
How about insects’ increased populations? Good news, winter weather has very little influence on insect populations if it is warm or extremely cold. Insects have developed excellent strategies to survive and are grouped into two categories: freeze tolerant and freeze avoiding.
Freeze-tolerant insects are able to withstand freezing conditions. These insects accumulate biological antifreeze in their cells prior to winter and use specialized carbohydrates as biological antifreeze. These compounds lower the freezing point of their body fluids, preventing ice crystals from forming inside the insects’ cells and killing them.
Freeze-avoiding insects just don’t hang around or expose themselves to cold conditions. Monarch butterflies migrate in the fall to Mexico where it is warm. Some insects such as Japanese beetles, June bugs, and dung beetles tap into the geothermal heat by burrowing into the ground to avoid a wintery death. The deeper you get in the soils, the steadier the temperature becomes.
The best predictor of insect survival is the conditions during insect emergence. They need food and need it quickly. For example, sometimes weather delays corn planting. This delay is detrimental to emerging corn rootworm larvae. If the insects do not have a food source, the first generation of the season will be greatly reduced. This can also lead to reductions of beneficial insects that feed on pest insects. Always cause and effect.
Predicting the long-term Georgia weather is near impossible. I need to just enjoy this early spring.
Reach Campbell Vaughn, the agriculture and natural resources cooperative extension agent for Richmond County, by e-mailing firstname.lastname@example.org.