Friday, November 27, 2015

Scab resistant cultivars shine in 2015

Kanza trees just before shaking, 2015
   During the rush of harvest, I've made two important observations about the impact of pecan scab on nut production.
   1. This past summer, I made the decision to concentrate the dollars we spent on fungicides to protect improved but scab-susceptible pecan cultivars such as Pawnee, Giles, and Chetopa. We made three fungicide applications on these trees and achieved good but not perfect results. This fall we were able to harvest good crops of quality pecans from most improved cultivars (Hirschi and Dooley were exceptions). In contrast, I decided save money by making only a single fungicide application to our native pecan trees in the hope we could suppress scab enough to ensure a decent native crop. Unfortunately, my gamble didn't pay off. We are harvesting far fewer native nuts that I originally expected. When I shake our native trees, I'm seeing far too many black, scabby stick-tights hit the ground. It seems that 2015 was not a good year to experiment in cutting back on fungicide costs.
   2. Once all the leaves fell from the trees this fall, I noticed that trees with genetic resistance to pecan scab tended to be the heaviest nut producers in 2015. The scab-resistant Kanza, Lakota, and Major trees all produced heavy crops of high quality nuts. Although our fungicide program provided fair scab control on scab susceptible cultivars like Pawnee, Giles, and Chetopa, yield for these cultivars were good but not great.
    The 2015 growing season has made many new believers in the need to propagate scab-free pecan cultivars in their orchards. I know I'm grafting only scab resistant cultivar on my home farm next spring.