Issue link: http://read.dmtmag.com/i/72545
VINEYARD SOIL & CELLAR be applied through foliar sprays. Many vineyard managers choose to use a combination of foliar and soil- applied nutrition. SPEEDY, YET TEMPORARY The advantage of foliar-applied nutrients is that it is a quicker meth- od to get nutrients to the vine com- pared to soil and root application. However, the supply is more tem- porary and the rate of uptake for leaves is generally much lower than the corresponding uptake of that nutrient through roots, given the same external concentrations of the nutrient. Foliar applications are helpful when a grower may want to apply fertilizers, yet soil moisture is low, and thus soil-applied fertilizers will have low mobility, or they may not want to fertigate if the vines don't need water. The period of reproductive growth of the vines, from bloom 6 5 through veraison, has limited root activity. Yet, it's a time when grow- ers often apply fertilizers, and foliar fertilizers may be more effective at this time. Additionally, many vineyard managers use sprays for mildew protection, so it is easy to add nutrients to an already planned mildew prevention spray applica- tion. With lower uptake rates, a few sequential applications can be used to more efficiently supply nutrients without over fertilizing, compared to larger soil-applied doses with less efficiency and larger risk of overfertilization. The disadvantages of foliar applications, in addition to having lower penetration rates than root- applied fertilizers, include runoff, washing off by rain, rapid drying of sprays, limited translocation of cer- tain nutrients from the leaf to other plant parts, and possible leaf dam- age if the nutrient concentrations are too high. Leaf damage is avoid- 4 3 ed by spraying at night or in day- time conditions with high relative humidity and low sunlight, and by adding silicon-based surfactants to the spray. Make sure to use a fertil- izer that is specifically prepared for foliar applications, and check the label for its compatibility with any other products you are including in the spray. ASSESSING UPTAKE RATES Although mineral nutrients in the form of atmospheric gases, such as sulfur dioxide, ammonia and nitro- gen dioxide, enter the leaf through the stomata, the uptake of min- eral solutes such as those applied through foliar fertilizer sprays occurs primarily through hydrophilic pores within the leaf cuticle. This is supported by research showing that ion uptake rates from foliar sprays are usually higher at night, when the stomata are closed, rath- 2 TOP-SELLING D profilalsace.us.com TRELLISING SYSTEM IN EUROPE C The EuroPost Patented CLICK LOCK® Cross Arm System B Maintenance Free Cost-Efficient Installation Mechanical Harvester Approved No Clips, Bolts or Nuts Necessary A Now available in the U.S. Exclusive Distributors: 6 WWW.VWM-ONLINE.COM 5 4 B ( 4:1 ) B CALIFORNIA - cvbsupply.com info@cvbsupply.com 3 2 8,4 JULY - AUG 2012 VINEYARD & WINERY MANAGEMENT 39 1 OREGON - ovs.com A D 1 C 5° 15° 9,63 2,33 28 - 0,5 +0 19,5 12,7 6,35 6,35 8,65 2 60° R1 R4 75°