Mar 16, 2012

Unseasonably warm weather puts fruit growers on alert

The growing season is off to a very early start across the Great Lakes and much of the central and eastern U.S., according to Jeff Andresen and Aaron Pollyea in the Michigan State University Extension Department of Geography.

"The abnormal warmth already has or will shortly bring most perennial crops and vegetation out of their protective dormant states," they report. "Given that this is taking place at least two full weeks or more ahead of normal, and that the relative susceptibility of plant tissue to frost and cold damage generally increases with increasing growth stage, there is an overall elevated risk of cold injury this spring season."

And even though current and long-term forecasts for spring call for more of the same general warm weather pattern, cold weather remains a very real threat.

"Further cold weather at some point in the next several weeks is virtually a certainty," they report.

For fruit growers, that means constantly assessing crops’ stage of development and their susceptibility to freeze injury, writes Mark Longstroth of Michigan State University Extension. During this unusual spell of warm weather, fruit trees will develop quickly. As buds start to swell, they lose the ability to withstand cold winter temperatures. Swollen fruit buds can often withstand temperatures in the teens without damage, Longstroth says, but temperatures in the low 20s can cause harm to open buds.

"Fruit trees will develop quickly and the critical temperature will rise from the teens to the 20s, to levels just below freezing at bloom time," he reports.

MSU Extension will be providing updates and advisories as the season unfolds.

http://news.msue.msu.edu/news/article/record_breaking_warm_weather_advances_beginning_of_growing_seasonMichigan State University Extension reports that a mild winter didn’t harm Southwest Michigan’s fruit plantings.

"Most plants were just waiting for warm weather," Most perennial fruit crops need temperatures above 42 F for growth and we have had lows in the 50s and highs in the 70s. The current heat wave with temperatures about 30 degrees above normal has caused rapid growth in perennial plants in across southern Michigan. This rapid growth should continue next week and will result in plant development being weeks ahead of normal. Winter’s coldest temperatures were on January 15 and February 11 with lows below zero. These cold temperatures caused little damage. The colds temperatures were recorded in lower freeze prone areas. Cold sensitive fruits such as peaches and wine grapes are normally planted in high sites where the temperatures were above zero. Soils are saturated with standing water in many blueberry fields. Now is a good time for applying soil active herbicides to control weeds. If you hurry there is still time to get dormant sprays on many fruit plantings. You can check for a local weather station at: www.enviroweather.com.