Issue link: https://read.dmtmag.com/i/629538
www.goodfruit.com GOOD FRUIT GROWER FEBRUARY 1, 2016 17 WINTER BUD BREAK 3-4 LEAVES BLOOM VERAISON HARVEST POSTHARVEST Trunk Trunk Trunk Trunk Trunk Trunk Trunk 3 FEET 0-0.1 0.1-0.2 0.2-0.4 0.4-0.7 0.7-1.25 1.25-2.5 ROOT DENSITY g/L soil* How grape root growth changes through the season The density of fi ne roots (the feeder roots that take up most of the water and nutrients) on grape plants changes according to plant needs, with the fewest fi ne roots found during bloom. SOURCE: JOAN DAVENPORT/WSU JARED JOHNSON/GOOD FRUIT GROWER Root densities were measured at a depth between 1 and 2.5 feet within a 3-foot radius from the trunk. (*g/L soil closely approximates inches per cubic foot of soil.) Fine roots Because fi ne roots are so tiny and would be destroyed or lost in the process of collecting and measuring coarse roots, the team collected soil samples in a radial pattern around the trunk to assess the distribution of fi ne roots. They then separated these roots from the soil. Fine roots were measured separately in the fi rst 12 inches in depth and again at a depth of between 12 and 30 inches. Fine roots grow and die. They decreased with depth, Davenport said, but depending on the time of year, they increased or decreased the closer or farther away they were from the trunk. Fine roots were densest at postharvest, with the fewest found at bloom. "By the time we get to bloom, the fi ne root density has declined dramatically at the surface and pretty much disappeared at the deeper depth," Davenport said. Fine root numbers then increased incrementally through veraison, harvest and postharvest, with fi ne roots growing at the expense of the coarse roots, she said. "This tells you how much the fruit is utilizing these resources and allows for more root growth after the fruit is harvested." People who manage crops tend to focus on the plants above ground and sometimes forget about the root systems, Davenport said, but they shouldn't assume that roots are growing just because they don't see them. "Know your roots," she said. In terms of the fi ne, feeder roots, it would be nice to have a lot of them during blooms, but the plant is so busy funneling its resources to its buds, that it "robs Peter to pay Paul," Davenport said. However, the exact opposite is happening at postharvest: The fruit is off the vines, and with shorter days and colder temperatures, the plant begins to send carbohydrates and nutrients to the trunk and roots to store for spring, causing a resurgence in fi ne root development. "Make sure you pay attention to that root growth and development when you're developing your irrigation management strategies," Davenport said. "Because there's a time when roots are growing or developing, and when you're stressing them with less irrigation, you're actually doing more damage than you know." • "Because there's a time when roots are growing or developing, and when you're stressing them with less irrigation, you're actually doing more damage than you know." —Joan Davenport Secure The Future of Agriculture Today Enhance the health and receptivity of the flower Increase activity of honeybees and other pollinating insects Increase germination rate and vigor of the pollen grain Effective with controlled pollination or when used alone Innovative, Established, State-of-the-Art Pollination Technology Developed and Patented by Thomas T. Yamashita, Ph. D F u s i o n P r o u d l y F e a t u r e s Specializing in products that offer growers An alternative to fumigation Superior foliar nutrition programs The ability to establish a superior Ecological Continuum 30+ years of proven field results Local representatives and distribution points through out WA, ID, OR, and CA Conventional Solutions and WSDA/CDFA Registered Organic Input Materials 1-888-634-F360 www.fusion360inc.com customerservice@fusion360inc.com