A partial diallel design was used to investigate the inheritance of tolerance to terbacil herbicide in cultivated strawberry, Fragaria ×ananassa Duch. Two tolerant cultivars, `Honeoye' and `Earliglow', two moderately tolerant cultivars, `Lester' and `Allstar', and two susceptible cultivars, `Red Chief' and `Guardian' were used as parents to create populations that segregated for tolerance to the herbicide. Tolerance rankings of the populations closely coincided with expected rankings based on the published tolerance levels of parental cultivars. `Honeoye' and `Earliglow' derived populations had the highest average tolerance ratings, while `Guardian' derived populations had the lowest tolerance ratings. Heritability was estimated at h2 = 0.50, indicating that significant progress in increasing the tolerance of new cultivars to terbacil can be achieved through traditional recurrent selection procedures. General and specific combining abilities suggest that the tolerant cultivars in this study may be fixed in their tolerance and that increased mean tolerance will be most apparent in progenies combining tolerant and susceptible cultivars. As such, a broader pool of germplasm may be needed to develop cultivars that are more tolerant than those in this study. Chemical names: terbacil (3-tert-butyl-5-chloro-6-methyluracil)
Eastern black nightshade is one of the problematic weeds in vegetables and soybeans in the Midwest. It is representative of a rapidly growing complex of broadleaf weeds where herbicide resistance would be expected to occur. Eastern black nightshade calli lines that are resistant and susceptible to acifluorfen were maintained on the medium without the herbicide. After two years, these lines were tested for tolerance to acifluorfen and paraquat. Tolerance to acifluorfen was maintained in the previously selected lines. The lines were also cross tolerant to paraquat. Plants were regenerated from these calli lines and grown in the greenhouse. 14C-acifluorfen and 14C-paraquat uptake, translocation, and metabolism were studied.
Greenhouse and field studies were conducted to determine the genetic relationship between bentazon tolerance exhibited by the pepper (Capsicum annuum L.) cultivars Bohemian Chili and Santaka, and to evaluate the importance of cytoplasmic factors in expression of the tolerance in `Bohemian Chili.' Greenhouse evaluation of parental and F2 populations of the cross `Santaka' × `Bohemian Chili' indicated that the major dominant gene conditioning bentazon tolerance in `Bohemian Chili' is probably the Bzt gene that conditions bentazon tolerance in `Santaka' or a gene closely linked to the Bzt locus. Field evaluation of F1 and F2 progeny populations of the cross `Bohemian Chili' × `Sweet Banana' in both `Bohemian Chili' and `Sweet Banana' cytoplasms demonstrated that cytoplasmic factors do not affect the expression of the bentazon tolerance gene in `Bohemian Chili.' We conclude that `Santaka' and `Bohemian Chili' are equally satisfactory sources of a bentazon tolerance gene for use in pepper breeding programs. Chemical name used: 3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide (bentazon).
suitable herbicide tolerance in newly emerging turfgrass species so as to minimize weed pressure during establishment ( Hoiberg et al., 2012 ; Venner, 2011 ). This is the first reported research in the literature describing the effect of a fall application
Four sweetpotato [Ipomoea batatas (L.) Lam.] clones were evaluated for metribuzin tolerance in greenhouse and field experiments. W-262 exhibited metribuzin response similar to the highly tolerant clone Tinian (U.S.P.I. 153655). SC 1149-19 was highly sensitive to metribuzin, and the commercial cultivar Jewel was intermediate in tolerance. Due to its more desirable horticultural characteristics and higher yields, W-262 is superior to Tinian as a source of metribuzin tolerance in sweetpotato breeding. Chemical name used: 4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one (metribuzin).
The herbicide metribuzin is registered for use on tomatoes (Lycopersicon esculentum Mill.). It is applied either preplant incorporated or postemergence. However, severe injury occurs when postemergence applications are made during low light conditions (1,2, 4, 5, 6). UGA 1113MT and UGA 1160MT are being released as sources of tolerance to metribuzin; both lines have exhibited excellent tolerance (no injury) to metribuzin applications (up to 16-times the recommended rate of 1.12 kg/ha) made during cloudy weather. Chemical name used: 4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4-H)-one (metribuzin).
Terbacil at 0, 0.28, 0.56, 0.84, and 1.12 kg·ha−1 was applied immediately after planting to strawberry (Fragaria xananassa Duch.) cultivars Surecrop, Honeoye, Guardian, Redchief, and Delite. Plant vigor and number of mother plants were reduced by all herbicide rates >0.28 kg·ha−1. ‘Delite’ plants were less vigorous at the time of planting than other cultivars. There were no differences between cultivars in number of rooted runners, but terbacil at rates >0.28 kg·ha−1 reduced runner rooting. Yield the year following planting was dependent on terbacil rate and cultivar. Vigorous cultivars (i.e., ‘Redchief) had superior yields. Terbacil at 0.28 kg·ha−1 was safe when applied to newly planted strawberries on soils with organic matter content of at least 1.0%. Chemical name used: 5-chloro-3-(l,l-dimethylethyl)-6-methyl-2,4(1H,3H)-pyrimidinedione (terbacil).
uninjured progeny were classified as tolerant and homozygous for an allele conditioning herbicide tolerance. Hybrids with sensitive and tolerant progeny were tested by χ 2 analysis for goodness of fit for segregation of tolerant:sensitive F 2 and testcross
Cupric hydroxide, copper ammonium carbonate, basic copper sulfate, mancozeb, and a combination of cupric hydroxide and mancozeb were applied to American black nightshade (Solanum americanum Mill) before treatment with paraquat at 0.6 kg a.i./ha. Paraquat efficacy was reduced by all fungicides/bactericides, except a flowable formulation of basic copper sulfate, when compared to the herbicide only control. Compared to a surfactant only control, efficacy 1 week after paraquat application ranged from 86% with paraquat only to 42% with a combination of mancozeb and cupric hydroxide. Mancozeb and mancozeb in combination with cupric hydroxide resulted in greater shoot dry weight than the paraquat only control when measured 2 weeks after herbicide application. Chemical names used: 1,1'-dimethyl-4-4'-bipyridinium ion (paraquat); Mn, Zn ethylene bis diethyldithiocarbamate (mancozeb).
Relatively few herbicides are registered in Alabama or in the southeastern United States for use in annual hill plasticulture production of strawberries. Acquisition of 24(c) special local needs status for certain herbicides could make more of these chemistries available to the strawberry industry. These herbicides, especially when applied as tank mixes pose potential risks to strawberry plant growth and fruit yield. Special local needs status for these herbicides has been granted for other states, but more evaluation of these products in Alabama soils under plastic mulch is needed. The objective of this study was to assess tank mix applications of preemergence herbicides with different modes of action on plant growth, crop yield, and fruit size of ‘Camarosa’ strawberry. A study was conducted at the Chilton Research and Extension Center in Clanton, AL, in 2018 and 2019. Pendimethalin (3.5 L·ha–1) and S-metolachlor (1.6 L·ha–1) were evaluated for potential phytotoxicity in ‘Camarosa’ strawberry when applied alone or in tank mixes with napropamide (8.6 kg·ha–1), sulfentrazone (0.3 L·ha–1), or terbacil (0.42 L·ha–1) by comparing them to a nontreated control. At 18 weeks after planting, pendimethalin tank mixed with napropamide reduced plant dry weight by 33% compared with the control, but this reduction was not significant. Additionally, tank mixes of pendimethalin with sulfentrazone, napropamide, and terbacil reduced shoot dry weight by 43%, 52%, and 43%, respectively, compared with pendimethalin alone. Pendimethalin + napropamide tank mix reduced relative growth rate by 95% compared with the control between 6 and 18 weeks after planting. All treatments were similar to the control in marketable yield. Differences in plant growth parameters did not appear to affect yield by the end of the experiment. All single applied treatments along with S-metolachlor tank mixed with napropamide and sulfentrazone; pendimethalin tank mixed with sulfentrazone and terbacil appeared to be safe for direct application to strawberry planting beds covered in polyethylene mulch.