Issue link: https://read.dmtmag.com/i/298602
42 MAY 1, 2014 GOOD FRUIT GROWER www.goodfruit.com resistance to root knot (Meloidognye hapla) or northern root knot. The grape-breeding program led by Dr. Andy Walker at University of California, Davis, has developed five new nematode-resistant selections, GRN1 to 5. According to literature, all five are resistant to root knot and dagger, though they vary in resistance to other nematode spe- cies. The five rootstocks have a range of vine vigor, from low to medium. "We're just now learning how they do under commercial settings," Cousins said. RS 2 and RS 9 were bred by USDA's Dr. David Ramming at Parlier, California, and selected by UC's Dr. Michael McKenry. Both have shown resistance to root knot nematodes and are rated as medium vigor, based on evaluations in California's San Joaquin Valley. Nemadex Alain Bouquet, a rootstock developed in France, is resistant to the dagger nematode X. index. About three-quarters of the vineyards in France have X. index populations, Cousins said. "This rootstock is only for the most vigorous sites because it is very slow growing." For those needing a more moderate vigor rootstock that is resistant to dagger nematodes, he suggested another UC rootstock, 039-16. "Breeding programs are coming up with new resis- tant rootstock, but it takes time to test new selections for disease, get material to commercial nurseries, ramp up propagation, and field test in different settings," he said. "It's a very detailed process." He cautioned Washington growers who have little rootstock experience to be aware of interaction between the scion and rootstock. Most nematode-resistant root- stocks are very intolerant of virus- infected scions. "Root- stocks are less tolerant of virus compared to own roots. It's not well understood why, but you need to be aware of the interaction of disease with rootstocks," he said. Choosing rootstocks A variety of high and low vigor rootstocks, each resis- tant to different nematode populations, is available, he said. Growers have to match rootstocks to their soil conditions and nematode species in their particular site. Reviewing research data of rootstock resistance can be "partly useful," he said. "It can vaguely point you in the right direction, but data usually don't tell you the whole story. There are hundreds of nematode species, and most research charts don't tell you what species or where the rootstocks were tested. The choice of rootstock for individual growers depends on pest pressure and soil type." He encourages growers to start by planting a few rootstocks to see how they perform. Growers in dry soil locations will probably want to use vigorous rootstocks because they are better at taking up water and supply- ing it to the scion, giving young plants a boost. Those with a high water table and deep soils should consider a devigorating rootstock. "The differences among rootstocks in deep soils with a lot of water are much less than those growing in a trial with limited soils and water," Cousins said. Vine productivity is also a factor. Pruning weight, fruit yield, and fruit quality are influenced by rootstock choice. In a California table grape rootstock trial, vines on Ramsey rootstocks produced the most fruit but also had the most cull fruit. Freedom had the most premium fruit while Harmony produced the fewest culls. "Your rootstock choice must factor in your needs of vine size, water relations, and nematodes," he said. "It's not just about the nematodes." • Consider for your next planting: • BRUCE PONDER • SUSAN WILKINSON • ADAM WEIL • DAVE WEIL 503-538-2131 • FAX: 503-538-7616 info@treeconnect.com www.treeconnect.com BENEFITS: • Disease tolerant • Cold hardy • Adapts well to all cherry-growing districts • Forms flower buds and comes into bearing quicker than Mazzard with a better distribution of flower buds Roots available for SPRING DELIVERY Call Tree Connection: 800-421-4001 Dwarfing Cherry Rootstock Krymsk ® 5 Krymsk ® 6 [cv. VSL-2, USPP 15,723] [cv. LC-52, USPP 16,114] "Krymsk ® 5 and Krymsk ® 6 cherry rootstocks have proven to be the best rootstock for our orchards. They are yield efficient, grow and adapt well, and are cold hardy." —John Morton The Dalles, Oregon DOUBLE WEED BOOM VICTAIR TRAIL TANK PAC MULE 3-POINT WEED SPRAYERS • Wheel follows contour– sprays even width • Boom telescopes–hydraulic cylinder available • Single side model–spray complete row • Boom accommodates various nozzles for special jobs • Chemical mow • 50, 100, 150, 200 gallon stainless steel tank • Full-length mechanical agitation • Line strainer • Deluxe agitator packing gland • Stainless steel lid and strainer • Tractor-mounted pressure regulator and control valves • Tank mounted on rubber saddles • Choice of diaphragm pumps • Suction shut-off valve • Liquid level sight gauge • 200, 300, 400, 500 gallon stainless steel tank • Line strainer • Full-length mechanical agitation • Suction shut-off valve • Deluxe packing gland bearings • Choice of diaphragm pumps • Tractor-mounted pressure regular and control valves • Tank secured on rubber- mounted saddles • Tires available from narrow to wide widths Heavyweight Performance! Lightweight Price! Mistifier Phone: 509-248-0318 • FAX: 509-248-0914 hfhauff@gmail.com • www.hfhauff.com • www.agpumpsonline.com "Rootstocks are less tolerant of virus compared to own roots." —Dr. Peter Cousins