Methyl bromide has been the foundation of chemical weed control in strawberry (Fragaria ×ananassa) in California for over 40 years. The impending phaseout of methyl bromide may leave strawberry producers dependent on less efficacious alternative fumigants for weed control. The use of herbicides to supplement fumigants is a potential weed control strategy for strawberry. A 2-year field study was conducted in California to evaluate 10 herbicides as possible supplements for methyl bromide alternative fumigants. Herbicides were applied immediately after transplanting (immediate posttransplant), and 3 weeks after transplanting (delayed posttransplant). Napropamide applied immediate posttransplant was included as a commercial standard. Immediate posttransplant treatments that were safe in strawberry include carfentrazone at 0.075 and 0.15 lb/acre (0.084 and 0.168 kg·ha-1), flumioxazin at 0.063 lb/acre (0.071 kg·ha-1) and sulfentrazone at 0.175 and 0.25 lb/acre (0.196 and 0.28 kg·ha-1). Triflusulfuron at 0.016 lb/acre (0.017 kg·ha-1) was the only delayed posttransplant treatment with acceptable selectivity. Among the selective herbicides applied immediate posttransplant, flumioxazin and napropamide provided the most consistent control of bur clover (Medicago polymorpha) and shepherd's purse (Capsella bursa-pastoris). Triflusulfuron applied delayed posttransplant did not significantly reduce bur clover densities, but did reduce shepherd's purse densities.
Grant R. Manning and Steven A. Fennimore
Gregory R. Armel, Robert J. Richardson, Henry P. Wilson, Brian W. Trader, Cory M. Whaley, and Thomas E. Hines
Protection, Greensboro, NC) at 4 g·ha −1 , halosulfuron (Sandea®; Gowan Co., Yuma, AZ) at 13, 20, and 27 g·ha −1 , sulfosulfuron (Maverick®; Monsanto Co., St. Louis, MO) at 46 g·ha −1 , cloransulam (FirstRate™; Dow Agrosciences) at 18 g·ha −1 , and tribenuron
Milton E. McGiffen Jr., Steven A. Fennimore, W. Thomas Lanini, and Carl E. Bell
The Food Quality Protection Act may result in the withdrawal from use of many herbicides in the “minor” crops: fruits, vegetables, herbs, flowers, and ornamentals. An obvious mitigation strategy is to test and register newer, low-rate herbicides that are currently used only in large-acreage field crops. The newer herbicides have low mammalian toxicity, few off-target effects, and are often used at rates of less than 0.1 kg/ha. Many of the older herbicides are applied at rates of several kg/ha and have off-target effects that can make their use problematic. Low-rate herbicides could replace the older chemicals commonly used in horticultural crops. We have tested several promising low-rate herbicides: carfentrazone, cloransulam, dimethenamid, halosulfuron, rimsulfuron, and sulfentrazone. Broccoli, cantaloupe, carrot, lettuce, onion, spinach, and processing tomato varieties were screened for tolerance to low-rate herbicides at four locations in California that included desert, inland, and coastal environments. All of the crops tested had tolerance for one or more of the low-rate herbicides. Data on similar tests for other horticultural crops will also be presented. The potential for registering these herbicides in vegetables and other horticultural crops varies with the crop and the pesticide's manufacturer. Pesticides that may soon face removal from widespread use will be reviewed. Herbicides and other potential alternatives to currently registered herbicides will be examined to determine possible practical alternatives for specific crops and weeds.
Richard G. Greenland
Few herbicides are available for weed control in carrot. Many of those that are available are old and are in danger of being discontinued. From 2000–04, field experiments were conducted on sandy loam soils at the Oakes Irrigation Research Site in North Dakota to evaluate some of the newer herbicides for possible use in carrot production. Herbicides were tested with preplant incorporated (PPI), preemergence (PRE), and/or several postemergence (POST) application timings. The major weed in this study was hairy nightshade. Cloransulam applied PRE severely injured carrot. Dimethenamid reduced carrot stand and isoxaflutole injured carrots when they were applied PRE. Neither controlled hairy nightshade when applied either PRE or POST, resulting in carrot yield reductions. Acetochlor reduced carrot stand when applied PRE and did not control hairy nightshade when applied either PPI or PRE, resulting in reduced carrot yield. Mesotrione killed carrots when it was applied PRE, but only slightly injured carrots when applied POST. Carrot yield was reduced in some years due to lack of hairy nightshade control when mesotrione was applied POST. Sulfentrazone reduced carrot stand and yield when applied PRE. It was less injurious to carrots when applied POST, but carrot yields were reduced in some years due to lack of hairy nightshade control. Flumioxazin severely reduced carrot stand when applied PRE. When it was applied after carrots were 8 cm tall, it slightly injured carrots, but did not reduce yield except in one year when it did not control hairy nightshade. None of the herbicides tested did consistently as well as the old standards of linuron, DCPA, and trifluralin, but flumoixazin, sulfentrazone, and mesotrione may hold some promise if applied POST.
Edmund J. Ogbuchiekwe, Milton E. McGiffen Jr., Joe Nunez, and Steven A. Fennimore
Preemergent and postemergent herbicides were evaluated in the Mediterranean climate of the southern San Joaquin Valley and the desert climate of the Imperial Valley from 1998 through 2000. Sixteen herbicide treatments were applied both as preemergence (PRE) and postemergence (POST) applications to carrot (Daucus carota L.). Carrot was generally more tolerant to PRE herbicide applications than to POST applications. Carrot was tolerant to PRE and POST imazamox and triflusulfuron at both locations. Carrot root losses due to herbicide were consistent with visual ratings. Treatments that injured carrot tops early in the growing season did not always reduce yield at the end of the season. PRE applications of imazamox and triflusulfuron did not affect carrot tops or the number or weight of marketable carrots. Carrots grown in the Imperial Valley and in the San Joaquin Valley were tolerant to PRE applications of carfentrazone, sulfentrazone, and imazamox. Results were similar for POST applications, although carfentrazone slightly injured carrot roots. PRE application of herbicides increased forked roots more than POST. Chemical names used: α, 2-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1, 2,4-triazol-1-yl]-4-fluorobenzenepropanoic acid (carfentrazone); N-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]me thanesulfonamide (sulfentrazone); N-(2 carbomethoxy-6-chlorophenyl)-5-ethoxy-7-fluoro (1,2,4) triazolo-[1, 5-c] pyrimidine-2-sulfonamide (cloransulam-methyl); 2-chloro-N-[(1-methyl-2-methoxy)ethyl]-N-(2,4-dimethyl-thein-3-yl)-acetamide (dimethenamid); (2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-(methoxymethyl)-3-pyridinecarboxylic acid) (imazamox); 3-chloro-5-[[[[(4,6-dimethoxy-2-pyrimidinyl) amino] carbonyl] amino] sulfonyl]-1-methyl-1H-pyrazole-4-carboxylic acid (halosulfuron); N-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]-3-(ethylsulfonyl)-2-pyridinesulfonamide (rimsulfuron); (methyl 2[[[[[4-(dimethylamino)-6-[2,2,2-trifluoroethoxy)-1,3,5-triazin-2-yl] amino] carbonyl] amino] sulfonyl]-3-methylbenzoate) (triflusulfuron).
Deniz İnci, Liberty Galvin, Kassim Al-Khatib, and Ahmet Uludağ
similar studies conducted with ALS inhibitors, C. canadensis populations were resistant to cloransulam, chlorimuron, imazethapyr, and bispyribac with the ranging 70, 40, 9.1, and 580, respectively ( Zheng et al., 2011 ). In addition, C. sumatrensis