NO. 3 1 Vinews Viticulture Information News, Week of 11 June 2018 Columbia, MO Herbicide Drift Damage Last week, I mentioned that damage from dicamba or other synthetic auxin herbicides would likely occur in the next 3-weeks. Damage from dicamba showed up this week on grapes and a nearby Red-bud tree. If your crop or other plants experience herbicide drift damage consider reporting the damage to the Missouri Department of Agriculture. For more information on what to do if your crop experiences herbicide drift damage. A B C D Herbicide drift damage from synthetic auxin herbicides occurred this week in Missouri on grapes (A, B and C) and a nearby Red bud tree (D).
2 Japanese beetles in full force Japanese beetles have been reported to have emerged near Cape Girardeau and Lamar in Barton County. Opposite sides of the state but both located in the in the southern part of the state. With more heat units accumulated this year compared to 2017, Japanese beetle emergence has been pushed forward a few calendar days. The hot temperatures will reduce the lifespan of the adult beetles, but don t depend on the high temperatures for management. It is difficult to know if adult emergence will be reduced by dry soil conditions. Low soil moisture during larvae development can result in some mortality of larvae and reduce the lifespan of emerging adults. However, remember that adult Japanese beetles are strong fliers. If you have irrigated turf areas near your vineyard then you should very well expect high populations of Japanese beetles. Japanese beetles have made their appearance for 2018. The beetles have been reported in both southern and northern counties. Dry droughty area expands to include central Missouri The high temperatures and limited rainfall in and around Missouri has resulted in the drought index map to expand to include large portions of central Missouri (see next page). How dry is it in some of the counties included in the drought index map? Both Boone and Gentry County are drier than for the same period as the drought of 2012. In fact, Boone County is about 6-inches drier compared to the same period during 2011 and 2012. On the other hand, Crawford County which is not included in the drought index map is fairing much better than Boone or Gentry counties. Although Crawford County experienced a dry spell for the last six-months of 2017, in 2018, Crawford County has received more than 22-iches of rain up to June 10. That is more precipitation than Boone and Gentry County have received combined for the period of January 1 to June 10, 2018. Table 1. Precipitation six months prior to 2012, 2017, and 2018 and precipitation from January 1, 2012, 2017, and 2018 to June 10 of each respective year. County 7.1.11 to 12.31.11 1.1.12 to 6.10.12 Period of precipitation 7.1.16 to 1.1.17 to 12.31.16 6.10.17 Inches 7.1.17 to 12.31.17 1.1.18 to 6.10.18 Boone 14.08 15.32 27.20 17.18 12.84 10.70 Gentry 14.23 11.22 20.26 14.50 14.18 5.56 Crawford 18.70 9.50 18.90 26.52 8.81 22.77
3 Irrigation Tips - Soil characteristics influence irrigation Clay soils absorb water very slowly and water moves slowly. Once clay soils are moist the soil retains a lot of moisture Clay soils should be irrigated slowly otherwise the water has a tendency to run-off. Apply water slowly over a long duration Water moves mainly by capillary action in clay soils. Water applied will move sideways and upwards in the soil profile Clay soils once wet should not need to be irrigated for several days On sandy loam soils the irrigation water should be applied quickly otherwise the water will move out of the root zone In contrast to clay soils, water in sandy soils moves by gravitational pull and therefore water moves down in the soil profile instead of sideways Sandy soils are irrigated more often than clay soils and water is applied quickly to reduce the influence of gravitational pull
4 Tomato Ringspot Virus (ToRSV) The dramatic symptoms of ToRSV were readily apparent on the grape cultivar Vidal this week. Vines infected with ToRSV often have aborted berries and berries of different sizes or hen and chicks. Aborted berries in ToRSV vines are likely the result of poor pollen germination. Previous ELISA testing of vines displaying symptoms gave positive Elisa test results. However, real-time PCR failed to detect ToRSV in 2017. This suggested that potentially a different ToRSV strain may be involved. Tomato ringspot virus is vectored by nematodes Xiphinema americanum which consists of a complex. Although once a vine is infected with ToRSV there is no cure. Tomato ringspot infected vines can be removed and the vineyard replanted with ToRSV resistant grape cultivars.
5 Cumulative Growing Degree Days for the Seven Grape Growing Regions of Missouri from April 1 to 11 June, 2018. Region Location by County Growing Degree Days 1 2018 2017 30 Year Average Augusta St. Charles 1116 1023 938 Hermann Gasconade 1045 958 920 Ozark Highland Phelps 1176 1075 991 Ozark Mountain Lawrence 1155 953 973 Southeast Ste. Genevieve 1122 1072 996 Central Boone 1137 959 919 Western Ray 1051 910 883 1 Growing degree days at base 50 from April 1 to June 11, 2018. Data compiled from Useful and Useable at https://mygeohub.org/groups/u2u/tools. Click on link below to determine growing degree days in your area. To determine the number of growing degree days accumulated in your area since April 1. Use this tool. Please scout your vineyards on a regularly scheduled basis in an effort to manage problem pests. This report contains information on scouting reports from specific locations and may not reflect pest problems in your vineyard. If you would like more information on IPM in grapes, please contact Dean Volenberg at 573-882-0476 or volenbergd@missouri.edu