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WWW.POTATOGROWER.COM 41 2359-25TriSteel12h.indd 1 6/4/19 9:26 AM when making mineral oil applications. If a portion of the crop canopy is not adequately covered, it is susceptible to transmission of PVY. Proper timing and rate of mineral oil applications is critical to ensure the best results. As new seed potato plants sprout from the ground (at between 20 and 50 percent emergence), it is time to start considering mineral oil applications. It may be possible to band the initial application in order to mitigate wasting products between rows. However, as the potato crop begins to fill out and mature, complete coverage is key to successful use of mineral oil. Broadcast application methods will ensure complete coverage is accomplished. Application intervals should correspond to crop growth, but never exceed seven days after the initial application. Many studies have shown the importance of frequent intervals ranging from five to seven days. This means applying mineral oil every five to seven days at least from 50 percent emergence through vine kill. If there is green tissue in the field, it is susceptible to PVY transmission. Even after vine kill, depending on the method used and level of kill, it may be necessary to make a final follow-up application of to those areas of the field that remain green. As seed potato fields begin to die, and other host crops have been harvested, a few pockets of remaining green seed potato plants act like a homing beacon to flying aphids. One of the critical errors made by growers is not protecting their crop through complete vine kill. As potato plants mature in the field, it is important that the mineral oil rate be sufficient to provide adequate coverage of the canopy. While low rates of mineral oil may produce positive results in some secluded areas, it is commonly recommended to apply at high label rates for increased protection against PVY. In several field trials, it has been reported that higher rates of mineral oil correlate to reduced transmission of PVY. Of course, historical concerns over the safety of high rates of mineral oil have driven rate decisions. Selecting a high- quality mineral oil is key to being able to apply higher oil rates with lower risk of phytotoxicity. PureSpray GREEN, an OMRI-listed organic mineral oil manufactured by Intelligro, is one mineral oil product with the high purity and flexibility to protect crops with little to no risk of phytotoxicity. It is a 99.9 percent pure mineral oil that has a CAS number of 8042-47-5, which guarantees there are no detectable aromatics or impurities left behind in the oil. One of the unique benefits of utilizing PureSpray GREEN in a PVY management program is that growers can use up to 1.5 gallons of oil per acre on label, providing great flexibility. Mineral oil is the primary management component of reducing in-season spread of PVY. A good IPM plan includes consistent intervals during the season, effectively coating the plants even through vine kill, and selecting the highest oil rate feasible. By following these principles, a high-quality mineral oil can be a significant tool in any grower's PVY management program. Bradley S Sladek is the technical services advisor for Intelligro. Learn more at www.intelligro.com.