Stretch of Warm Weather Puts Fruit Growers at Risk

Mar 20, 2012

Many of us are enjoying this unseasonably warm weather.  But for some farmers, it’s nerve-racking,  especially for fruit growers.  Fruit trees are starting to sprout two or more weeks ahead of time.  It’s only March, so cold weather is very likely to come back and kill off those early-blooming crops.

Jeff Andresen is the state climatologist and an associate professor of geography at Michigan State University.   He tells WKAR’s Gretchen Millich that when it comes to this early stretch of warm weather,  Michigan farmers are “sailing in uncharted waters.”

JEFF ANDRESEN:  We have just been through an unusually mild winter.  It turned out to be the fourth mildest winter on record in over 100 years.  So, the winter temperatures were very, very odd, and during the last one to two weeks, we saw an intensification of a jet stream pattern that has been present with us really all the way back into the late fall and early winter.  That also is very, very unusual, but during the last week or two, we’ve been under the influence of air masses from sub-tropical origins.

That in itself is not extremely unusual, but it is for this early in the season to see air this warm and for this long, that is very, very odd.  As we look at previous warm Marches on record, 1945 stands out, in most locations in the state, as the warmest March on record.  But indications are now, there’s a fairly strong likelihood that by the end of the month, March of 2012 will become the warmest March on record.  Not only will it become the new record, it will shatter the old record, I think, with some to spare.  So, what we are seeing right now truly is something historical.

GRETCHEN MILLICH:  This may be pleasant for people who want to get out in their shorts and their flip-flops, but this presents some real challenges for growers, and some crops are riskier than others.  Can you describe what’s happening now and who’s really affected by it?

ANDRESEN:  All cold-blooded organisms are dependent on temperature for their rates of growth and development, and this year, because of the abnormally early warm-up, we’ve seen both natural or native and then agricultural species come out of their protective states of dormancy early.  In some cases, we might be talking almost a month earlier than they typically do, and the problem is that, as they do begin growth and development, those plants are left relatively much more vulnerable to freezing temperatures, should they occur.  Their ability to withstand cold temperatures is much less than it was when they were dormant.  If you asked a fruit grower what type of weather pattern they would like in the spring, it would probably be one of the only groups that said we want cold temperatures, we want winter to continue on into the season, because many of the years we do see early warm-ups, we also then unfortunately do see subsequent losses with cold damage in buds that are killed by freezing temperatures.

The sobering thing for us to remember is that when we examine the frequency of cold temperatures in April, May and June, we have had freezing temperatures, for example, in the East Lansing area all the way into the beginning of June.  So, that in itself shows us that the weather patterns do change and that the risk of seeing freezing temperatures from here on out is very, very high, although the other caveat is right now, we do not see any sign of cold air or a cold air mass making it down to the Great Lakes anytime soon, at least for the next week or two.  But, as climatology statistics remind us, it does happen.  So, at some point, probably in April if it does happen, we will see at least a temporary reversal or a return of cold weather, as strange as that seems right now.

MILLICH:  Is there anything good about having a mild winter and having this warm weather now?  Is there anything about this whole phenomenon that’s a positive thing for growers?

ANDRESEN:  For many types of agriculture, I think that there are more negatives than positives.  One of the other ones that we don’t think about is that many potentially destructive insect pests that would be killed by our winters were able to survive this winter, and the pest pressure may be a little bit higher than it normally is.   There are some instances, though.  These very unusually warm temperatures accelerate evaporation.  So, one positive potential is here is we might be able to get out and do our spring field work.  Spring tillage probably will take place much earlier than it typically does.

Also, in some instances for growers who produce hay and other forages, if we have a wet year, there’s a potential that we would have an extra-long growing season.  But right now, I think really the big concern is for our perennial crop, especially the fruit crops.  They’re going to be vulnerable for a longer period of time than they typically are, and that translates directly into more risk for the growers.  That, of course, is a negative.