As I walk the walnuts - 3

As I walk the walnuts, or more accurately, pass through on snowshoes, as we had about 25cm of the white stuff on Friday, I look ahead to the coming season and wonder what’s in store for us. Maple syrup production has turned into a big gamble, because of early sap flow when the temperature spikes, and a friend of mine wonders whether it will ever be worthwhile tapping the trees again. He’s slowly building a new sugarhouse, in case he becomes so inclined, but it doesn’t look as though it will be worth his time hurrying this year. The corollary for a nut producer is those aggravating late frosts in May, which can sweep the trees clean of the emerging flowers. So far, the walnuts will take 2^oC up until the end of the first week of May, after which it is a complete gamble. Last year, a frost on May 19^th did widespread damage, though it didn’t come close to the two consecutive nights of -5 ^oC we recorded about the 8^th May in 2005.

Common sense says we need to track the phenology of flowering, because later emerging flowers stand a better chance of missing the frost. However, this is a laborious task, which would require scoring all our trees. Well, you say, you already score for disease expression and nut production, why not phenology? Well, I say, if a tree bears nuts after a frost in the critical period I mentioned, there’s a good chance it did so because it flowers late, i.e. I’d rather score the result than the cause. However, now that I have this indicator, it would be a good idea to track the phenology of flowering on the 25 trees from which I on-planted last fall. My hypothesis is that all valuable traits have at least some measurable heritability from the maternal line, and that I need to determine whether the average expression of each trait in the population of offspring is at least marginally better than that same trait expressed in the maternal tree, i.e. that I can make genetic gain by selecting under our conditions for nut yield, kernel quality or whatever other characteristic I believe valuable. However, it takes that first effort at on-farm selection to know whether it is worthwhile (equivalent to concentrating beneficial characteristics in a smaller population than the one from which the selections originated).