The last couple years have been particularly rough on our experimental orchard here on the farm. We have 27 different varieties of apple trees, three sour cherry trees, seven plums, six pears, three apricots and one peach. We also have numerous vines and berry bushes. My goal is two fold, to have fresh farm grown fruit from May until October and to see what trees and bushes are really best suited for our harsh climate. I am also interested in promoting other local enterprises using locally grown fruit. Many of the trees in our orchard have been struggling a lot over the past two summers due to a few things: extreme winter conditions, hail and disease. The largest issue is cold weather and erratic temperature variations over the last couple of winters. The winter of 2013 was more like the winters I remember growing up on the northern Montana prairie as we reached 34 below zero on December 7th. Our climate zone is 3, which means we can expect to reach 40 degrees below zero in the winter time. However, for the past several years we have not seen temperatures colder than 30 below zero, which would mean we were now more like zone 4. So 33 below put us back into zone 3 for sure.
This cold snap gave me a chance to see how hardy the fruit trees I had chosen really were. This low temperature resulted in severe freeze damage to two of my apple trees. It killed my peach tree which had survived the two previous winters and also killed all the fruit spurs on my pear trees so I have had no blossom on any of these trees for the past two years. This last winter, in 2014, it didn’t get nearly as cold but we experienced a sudden drop in temperature in early November when the weather changed from a very warm Fall of 50’s and even 60’s right up until November 8, and then on November 11 the temperature dropped to 9 degrees below zero. Most trees in our area can adapt to a slowly dropping temperature going into the winter, which gives them a chance to harden off. This last fall however, the trees were unprepared for the sudden onset of winter. That resulted in the death of three sour cherry trees, two apple trees, two apricot trees and one pear tree. Nearly half of the rest of my apple and pear trees were severely damaged. Another problem we have during the winter is several extreme temperature fluctuations caused by unusually warm “chinooks”. A “chinook” is a Native American word that means warm wind. While they certainly provide a welcome break in the long cold of winter, they can confuse trees into believing spring is approaching and if tender buds break dormancy and then are exposed to another blast of very cold weather they can be killed. We think that is what killed the fruit spurs on the pears last year and also did some damage this year, as we had more cycles of very cold temperatures and much warmer chinooks than usual these last two winters. Because of these problems, of the 27 apple trees we have in the orchard, only seven are producing fruit. Then the weather threw us for another loop earlier this summer with a hail storm on June 4th. This is the third hail storm we have received in three years which is very unusual for us. There was a lot of damage to our orchard. The damage was easiest to see on the fruit or the torn leaves, but the trunk and branches were damaged as well.
Winter kill and hail storms can make trees more susceptible to disease. Winter kill weakens the trees immunities while hail storms expose the vulnerable tissue of the tree. Several of our trees are showing moderate to severe signs of fireblight. As mentioned when we were pruning earlier this spring, fireblight is extremely contagious. It can be spread by bees or other insects, even by the wind or rain if the tree is wounded by something like hail. We will trim off the effected branches and will probably replace all the winter damaged trees, many of which were semi-dwarf, with standard size trees which are more hardy than semi-dwarf and which are also hardy to zone 3.