Spot applications of glyphosate at the same rate previously mentioned were also utilized to control perennial weed species, Canada thistle and field horsetail , within all plots. Weed control treatments were initially applied in the spring of 2008. Data were collected for the growing seasons of 2008 and 2009. Dormant season data were collected in the springs of 2009 and 2010. Annual weed control was evaluated twice per season at 10 and 20 weeks after application . Weed control was quantified as percent control by visual inspection compared to weed presence in an untreated plot margin near the treated row where 0 equated to no control and 100 indicated complete plant death or no plants present outdoor cannabis grow.Plant growth was evaluated as vine shoot length and biomass production through dormant pruning weight. Each measure was averaged for the two vines within each sub-plot for analysis. Plant shoot lengths were measured during the dormant season as the length of the combined trunk and cordon from ground level.
Dormant pruning weight was determined as the total fresh weight of one-year-old wood removed. In both years, each vine was pruned under the same goals of removal of dead material, trunk and cordon establishment, reduction in the number of trunks, and removal of undesirable lateral branches. Effects on vegetative bud-break timing were monitored as the number of Julian days prior to the first unfurled leaf. Values were averaged over the two vines within each cultivar subplot for analysis. Bud hardiness was evaluated each spring as the number of viable primary buds in a 50 bud sample taken from 10 random stems during dormant pruning. Randomly selected buds were sampled from stems with different diameters and from different positions in order to be representative of the entire vine. Viable buds were determined as buds that retained green tissue in the primary bud Primary buds that were brown were considered not viable. Soil temperature was monitored using thermistors and soil water content was monitored using soil probes with periodic recording after calibration for the soil type. Thermistors and soil water content probes were placed in the center of each main-plot at a depth of 15 cm. Temperature and moisture content were recorded hourly from July 8 to November 13 during the summers of 2008 and 2009.
Values were averaged monthly for analysis. Data were subjected to analysis of variance using proc mixed with SAS statistical analysis software . Treatment effects on plant growth and development were evaluated as randomized complete block designs with a split-plot arrangement with four weed control methods as wholeplots and four cultivars as subplots with three replications. For weed control and soil conditions, data were evaluated as a randomized complete block design with four weed control treatments and three replications cannabis grow equipment. Years were treated as repeated measures. Months were treated as repeated measures when soil temperature and moisture content were evaluated and were independently evaluated for weed control data. Cultivars differed in their combined trunk and cordon establishment. MN 1131 had longer shoots compared to either DM 8521 or St. Croix indicating greater progress toward establishment. The applied weed control treatments did not affect the rate of trunk and cordon establishment in the current study . Dormant pruning weights also did not differ among weed control treatments or among cultivars in the two studied years . Overall, impacts on growth rate and progress toward vine establishment were caused by cultivar differences and were not attributable to weed control methods.
There were no significant deficiencies caused by the alternative weed control measures, thus mulches may be considered acceptable weed control methods in North Dakota vineyards during establishment. St. Croix broke-bud significantly later than DM 8521 and MN 1131 , while MN 1200 did not differ from any other cultivar. The interaction between weed control method and year also showed significant variation . When tests of simple effects were used to evaluate the variation within each year, treatments significantly varied in 2009, but not in 2010. In 2009, vines in plots where herbicide was used broke-bud as much as five days earlier than vines in plots treated with mulch. The early bud-break of these vines may lend them more susceptible to late spring frosts in certain years. It was anticipated that the mulches would delay bud-break due to their moisture conserving and soil cooling effects .