Issue link: http://read.dmtmag.com/i/489844
www.goodfruit.com GOOD FRUIT GROWER APRIL 15, 2015 13 Geneva 935 has been classified in New York as having the same vigor as Malling 26, but has proven closer to M.9 Nic 29 size in Washington. It is tolerant of replant disease and resistant to fire blight. rootstocks are about 40 to 45 percent the size of a seedling tree and are resistant to fire blight and woolly apple aphid. Though larger than Malling 9, these rootstocks could have a place in modern plantings, Auvil said. "I think that, looking down the road towards automated harvest and multiple-leader trees, we have the ability to have rootstocks with a little more horsepower and yet excellent crop density to allow thinner production systems and high yields." The new trial also includes G.11 (CG.3011), G.30 (CG.5030), G.41 (CG.3041), G.935 (CG.5935), and G.214 (CG.4214) along with the new selections CG.4011 and CG.5257. The standard root- stocks Budagovsky 9, M.9 Nic 29, and M.9 T337 are included for comparison. Fazio said nurseries have asked for CG.4011 and CG.5257 to be sent to the National Clean Plant Network for certi- fication and testing, and his unit is pro- viding certified material for large-scale testing. They are both relatively easy to propagate. CG.5257 is resistant to woolly apple aphid, but CG.4011 is susceptible. They are both resistant to fire blight. They are very precocious and seem to do well in replant situations. A new rootstock nearing release, which is not included in the trial, is G.814 (CG.4814), which Fazio said has several interesting traits. It is productive, cold hardy, resistant to fire blight, tolerant of replant disease, provides a good amount of calcium to the scion, and is easy to propagate. However, it has the same failing as G.16—it is susceptible to one or two latent viruses. "The virus issue on this rootstock is going to be a deciding factor on who propagates it, because we will need assur- ance that the nurseries and growers know how to handle it," Fazio said. Older trial Earlier this year, Auvil led a tour of a 10th-leaf trial of disease-resistant and replant-tolerant rootstocks in Wapato, with Gala as the scion. The trees have cropped heavily for the past three years. Yields from trees on M.9 have plateaued but yields from trees on most of the Geneva rootstocks have continued to increase. They are looking healthy and vigorous, whereas those on M.9 are looking tired, Auvil pointed out. Some trees on B.9 in the unfumigated treatment didn't make it past the first two or three years, lacking enough bearing surface to support the crop. G.11 is a weaker rootstock than M.9 but has overtaken M.9 in the fumigated plot, producing 293 bins per acre over the first seven years. However, it is not tolerant of replant disease. G.41, a slightly larger rootstock than M.9, outyielded M.9 in both fumigated and unfumigated treatments with yields of 307 and 227 bins respectively. G.210, which is more vigorous than M.9 and G.41, has performed surprisingly well in replant conditions, Auvil reported. Cumulative yields in the first seven years were the equivalent of 312 bins per acre in the fumigated plot and 328 bins per acre in unfumigated ground. In comparison, cumulative yields on M.9 EMLA were 253 bins from fumigated trees and only 176 bins from unfumigated. G.30 has also proven reliable in unfu- migated ground, but its future may be limited because of the difficulties nurs- eries have in propagating it. In almost all the trials that the Research Commission has conducted, trees on G.30 have con- sistently been the highest yielding, Auvil said. At the Wapato trial, cumulative yields on that rootstock were 412 bins per acre in fumigated ground and 371 bins per acre in unfumigated. "But it's a miserable thing to grow in the nursery," he said. G.890 is similar to G.30 in vigor. In a trial of a similar age in Brewster, Washington, with Fuji as the scion, it's done extremely well in light soils and difficult replant conditions, Auvil reported. • GERALDINE WARNER/GOOD FRUIT GROWER Contact your local crop advisor or dealer, or visit cheminova-us.com FUNGICIDE Specialty Crops Give your crop the advantage This season make TOPGUARD® Fungicide Specialty Crops your ĮƌƐƚĂƉƉůŝĐĂƟŽŶƚŽƉƌŽǀŝĚĞĞĂƌůLJĐŽŶƚƌŽůŽĨƉŽǁĚĞƌLJŵŝůĚĞǁŝŶLJŽƵƌ ƉŽŵĞĂŶĚƐƚŽŶĞĨƌƵŝƚĐƌŽƉƐ͘LJƌĞĚƵĐŝŶŐŝŶŽĐƵůƵŵůĞǀĞůƐ͕ ŝƚǁŝůůůŽǁĞƌƚŚĞŝŵƉĂĐƚŽĨŽǀĞƌͲǁŝŶƚĞƌŝŶŐĨƵŶŐŝĂŶĚŐŝǀĞLJŽƵ ĂŶĂĚǀĂŶƚĂŐĞƚŽƐƚĂƌƚƚŚĞƐĞĂƐŽŶ͘ ŌĞƌƚŚĞĮƌƐƚĂƉƉůŝĐĂƟŽŶ͕ŝŶĐŽƌƉŽƌĂƚĞTOPGUARD Specialty Crops ĂƐĂǀŝƚĂůĐŽŵƉŽŶĞŶƚŽĨLJŽƵƌĨƵŶŐŝĐŝĚĞƉƌŽŐƌĂŵƚŽŵĂdžŝŵŝnjĞ LJŽƵƌĨƌƵŝƚƋƵĂůŝƚLJĂŶĚƚƌĞĞŚĞĂůƚŚ͘ ůǁĂLJƐƌĞĂĚĂŶĚĨŽůůŽǁůĂďĞůĚŝƌĞĐƟŽŶƐ͘dKW'hZ&ƵŶŐŝĐŝĚĞ^ƉĞĐŝĂůƚLJƌŽƉƐŝƐŶŽƚƌĞŐŝƐƚĞƌĞĚŝŶĂůŝĨŽƌŶŝĂ͘ ΞϮϬϭϱŚĞŵŝŶŽǀĂ͕/ŶĐ͘dKW'hZŝƐĂƌĞŐŝƐƚĞƌĞĚƚƌĂĚĞŵĂƌŬŽĨŚĞŵŝŶŽǀĂ͕/ŶĐ͘