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Yellow nutsedge (YNS) can be a serious problem where vegetables are grown on polyethylene mulch. YNS will rapidly cover the row and become a nuisance. This study was conducted to determine the effect of various population densities of YNS on the yield response of yellow squash grown on black polyethylene. Presprouted YNS tubers were planted at densities of 0, 10, 20, 40, and 50/m2 the day after `Superpik' yellow squash was planted. In 1996 the YNS did not produce tubers. Top growth increased up to 40/m2, but root growth increased to 50/m2. In 1997 top and root growth increased up to 20/m2. Tuber production increased up to 40/m2. In 1998 top, root, and tubers dry weight increased as the YNS density increased to 50 tubers/m2. There were no differences in weight of the squash plants or fruit yields any year. In experiments over three growing seasons, YNS at the densities tested did not interfere with the yield of yellow summer squash grown on black polyethylene mulch. The rapid growth of the squash and its dense canopy provide too much shade for the YNS to grow competitively. The yield of the YNS was greater in wet years than in dry years. The increased supply of YNS tubers could cause squash yield reductions in future plantings because of potential densities greater than those use in this study. YNS competition could also be a problem in rotational crops that are less competitive.
Abstract
The marketable yield of bell peppers grown on aluminum-painted polyethylene was significantly greater as compared to that obtained from diphenamid herbicide or hand-cultivated treatments for 2 years, and black polyethylene for 1 year. Two plants in a hill planted in 2 rows on a bed significantly increased yields over double rows of single plants or single rows of single plants on a bed. Average fruit weight was greater from plants planted in a single row.
The Precision Cultural System (PCS) developed by the Louisiana Agricultural Experiment Station allows simple and precise cultivation of vegetable crops; however, speed of the cultivators in small vegetable crops has been limited. The standard PCS sweep cultivator was limited to about 1.6–2.4 km·h–1 in small crops because it would throw soil over the crop plants at higher speed. The standard PCS rotary tiller cultivator could operate at 3.2–4.8 km·h–1 in small crops but could not be operated faster in larger crops, due to its tendency to “walk” out of the soil at higher speeds. The standard PCS sweep cultivator was modified by replacing the sweeps between the twin drills with two pairs of straight finger-wheel (“rolling cultivator”) spiders non-angled and in tandem. The finger-wheel gangs on the bed sides were also inactivated by raising them above the soil. The resulting PCS cultivator was successfully operated in very small crop plants (≤25 mm high) at speeds of 8–10 km·h–1 with no crop damage. The cultivator could then be easily refitted for standard sweep cultivation on subsequent passes. No reductions in weed control or yield of mustard, kale, turnip, or spinach were noted when using the high-speed system.
Abstract
Fresh and dry weights of the above ground plant of ‘Copper Skin Jewel’ and ‘Jewel’ sweet potatoes (Ipomoea batatas (L) Lam.) increased with soil warming but total yield of roots was unaffected. Soil warming increased root size, root epidemal color intensity, and improved internal color but decreased percent dry weight, and root pH. Evaporative cooling reduced the foliage weight, storage root fresh weight and total weight of ‘Jewel’ but not of ‘Copper Skin Jewel’. Subirrigation did not influence any of the parameters mentioned above.
Field studies were performed on established carpetgrass (Axonopus affinis Chase) in 1994 and 1995 to evaluate plant growth regulators (PGRs) and application rates. Trinexapac-ethyl (0.48 kg·ha-1) improved turf quality and reduced cumulative vegetative growth (CVG) of unmowed and mowed plots by 38% and 46%, respectively, in 1995, and suppressed seedhead height in unmowed turf by >31% 6 weeks after treatment (WAT) both years. Mefluidide (0.14 and 0.28 kg·ha-1) had little effect on carpetgrass. Sulfometuron resulted in unacceptable phytotoxicity (>20%) 2 WAT in 1994 and 18% phytotoxicity in 1995. In 1995, sulfometuron reduced mowed carpetgrass CVG 21%, seedhead number 47%, seedhead height 36%, clipping yield 24%, and reduced the number of mowings required. It also improved unmowed carpetgrass quality at 6 WAT. Sethoxydim (0.11 kg·ha-1) suppressed seedhead formation by 60% and seedhead height by 20%, and caused moderate phytotoxicity (13%) in 1995. Sethoxydim (0.22 kg·ha-1) was unacceptably phytotoxic (38%) in 1994, but only slightly phytotoxic (7%) in 1995, reduced clipping yields (>24%), and increased quality of mowed carpetgrass both years. Fluazasulfuron (0.027 and 0.054 kg·ha-1) phytotoxicity ratings were unacceptable at 2 WAT in 1994, but not in 1995. Fluazasulfuron (0.054 kg·ha-1) reduced seedhead height by 23% to 26% in both years. Early seedhead formation was suppressed >70% when applied 2 WAT in 1994, and 43% when applied 6 WAT in 1995. The effects of the chemicals varied with mowing treatment and evaluation year. Chemical names used: 4-(cyclopropyl-x-hydroxy-methylene)-3,5 dioxo-cyclohexane-carboxylic acid ethyl ester (trinexapac-ethyl); N-2,4-dimethyl-5-[[(trifluoro-methyl)sulfonyl]amino]phenyl]acetamide] (mefluidide); [methyl 2-[[[[(4,6-dimethyl-2-pyrimidinyl) amino]carbonyl] amino] sulfonyl]benzoate)] (sulfometuron); (2-[1-(ethoxyimino)butyl-5-[(2-ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one) (sethoxydim); 1-(4,6-dimethoxypyrimidin-2yl)-3-[(3-trifluoromethyl-pyridin 2-yl) sulphonyl] urea (fluazasulfuron).