Eastern Black Nightshade Management in Plasticulture Tomatoes
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Date
2005-07-31
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Field experiments were conducted to determine density-dependent effects of eastern black nightshade season-long interference on tomato yield loss when growing in-row with plasticulture tomato. Eastern black nightshade was transplanted at densities 0, 1, 2, 3, 4, and 5 per planting hole. Percent yield loss for weight of culls, threes, medium, large, or extra large grades, or marketable, total, or sum of large, extra large and jumbo grades, was not affected by eastern black nightshade density, but for jumbo grade fruit, the premium grade, yield loss as affected by eastern black nightshade density followed a rectangular hyperbola model. Estimated coefficients for A (maximum yield loss) and I (yield loss per unit density as density approaches zero) was 84 and 116, respectively. LSD comparison of mean yield showed a reduction for densities 1 to 5 weeds per hole for number and weight of extra large, jumbo, marketable, and total fruit categories from the weed-free, but no difference among densities 1 to 5 weeds per hole, while mean for number and weight of culls, mediums, and large grades did not differ by any density, suggesting eastern black nightshade causes tomato quality loss. Values of large and extra large were not affected by eastern black nightshade density, but value of jumbo fruit and the value of the sum of large, extra large, and jumbo grade varied by the densities tested. The economic threshold for jumbo grade was one weed per 11.25 m of row (with 45 cm crop spacing).
Field experiments were conducted to determine the effect of eastern black nightshade on tomato yield loss growing in-row with plasticulture tomato, as well as eastern black nightshade berry production and seed viability. Eastern black nightshade was transplanted at 1, 2, 3, 4, 5, 6, and 12 weeks after tomato planting (WAP) and remained until tomato harvest, or was established at tomato planting and removed at 2, 3, 4, 5, 6, and 8 and 12 WAP to determine the critical weed-free periods. Seed viability of medium and large berries was 7 to 100% and increased with length of establishment or removal time. Extra small and small berries had negligible viability of 0 to 15 %. The critical weed-free period to avoid viable seed production was 3 to 6 WAP. No treatment differences in tomato yield were found in year 1. In year 2 at the first location, weight of three-grade fruit varied by establishment time. In year 2 at the second location, differences in the sum weight of extra large and jumbo grades occurred. The critical weed-free period to avoid greater than 20 % yield loss for the sum weight of extra large and jumbo grades was 29 to 48 days after tomato transplanting, and was economically justified based on 2004 tomato prices during weeks harvested.
Field experiments were conducted in 2003 to identify those herbicides that were safe to tomato postemergence directed in plasticulture tomato and in 2004 to determine the effect of these herbicides postdirected at various rates on tomato injury and weed suppression. Apple of Peru, eastern black nightshade, fall panicum, goosegrass, hairy galinsoga, ivyleaf morningglory, jimsonweed, johnsongrass, large crabgrass, Mexican groundcherry, pitted morningglory, redroot pigweed, sicklepod, and velvetleaf were tested. In 2003, treatments (expressed as g / ha) were 17.3 cloransulam-methyl, 70.1 and 105.4 flumioxazin, 25.8 and 38.7 halosulfuron, 34.4 and 51.6 imazamox, 275 metribuzin, 1.6 and 2.6 thifensulfuron, and 7.8, 15.7, and 31.4 trifloxysulfuron sodium. With the exception of cloransulam-methyl at Clinton which caused 11% injury, cloransulam-methyl, flumioxazin and imazamox gave 24% or greater visual injury to tomato. Likewise, marketable fruit weight was 16 to 71 % of the nontreated check for these herbicides. Tomato was injured 5% or less by all rates of halosulfuron, metribuzin, thifensulfuron, and trifloxysulfuron sodium and yielded similar to tomato in the nontreated control for these treatments. Thus cloransulam-methyl, flumioxazin, and imazamox were too injurious to tomato and excluded from 2004 studies. In 2004, treatments were 5.6, 8.4, 11.2, 16.8, and 33.4 trifloxysulfuron sodium, 275 metribuzin, 3.7, 4.7, and 5.8 thifensulfuron, and 38.7 halosulfuron. Again no differences from the non-treated control were found for tomato yield for these herbicides. Trifloxysulfuron sodium controlled apple of Peru, eastern black nightshade, jimsonweed, and Mexican groundcherry. Thifensulfuron controlled redroot pigweed, velvetleaf, Mexican groundcherry, hairy galinsoga, and jimsonweed. Metribuzin and halosulfuron consistently provided excellent control of Mexican groundcherry, velvetleaf, redroot pigweed, hairy galinsoga, and jimsonweed. Metribuzin consistently provided excellent control of sicklepod, apple of Peru, and eastern black nightshade.
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weed density, critical weed free period
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Degree
MS
Discipline
Horticultural Science
