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Greenhouse and field trials were carried out to evaluate carfentrazone as a potential tank mix with glyphosate to control weeds. Application of active ingredient glyphosate at 1.15 kg·ha−1 provided 44%, 50%, 19%, and 17% control of ivyleaf morning-glory, milkweed vine, hemp sesbania, and field-bind weed (stage 1), respectively, and increased to 45%, 51%, 31%, and 76%, respectively, with active ingredient of 2.30 kg·ha−1. Carfentrazone as active ingredient at 17.7 g·ha−1 achieved 53%, 90%, and 99% control of hemp sesbania, ivyleaf morning-glory, and milkweed vine (stage 1), and increased to 88%, 98% in first two weed plants, respectively, with active ingredient at 52.2 g·ha−1. Either rate of carfentrazone at any stages of field-bind weed yielded ≈100% control. Application of tank-mixed glyphosate and carfentrazone to ivyleaf morning-glory and hemp sesbania (stage 1) demonstrated greater control than their sole applications. A complete control of milkweed vine and field-bind weed (stage 1) was achieved by tank-mixed glyphosate and carfentrazone. Corresponding to percent control values a reduction in biomass value was also recorded. Biomass reduction with glyphosate at either stage of ivyleaf morning-glory was only 14%–24% and reduction with carfentrazone was 40%–47%. Biomass was further reduced with the tank-mixed glyphosate and carfentrazone. A similarly trend in biomass reduction was noted in milkweed vine and hemp sesbania. However, ivyleaf morning-glory was found to be the most tolerant weed to glyphosate followed by hemp sesbania, milkweed vine, and field-bind weed. Tank-mixed applications of these two herbicides further increased the percent control and biomass reduction. In all weed species, there was a significant decrease in percent biomass reduction with age. Although the types of weed were different in the field experiment and greenhouse, a similar trend was observed in the percent control achieved with glyphosate, carfentrazone, and their tank-mixed application. Tank-mixed applications achieved 93%–95% control of Brazil pusley and 75%–83% control of passion flower. These values were significantly higher than the percent control achieved with application of only glyphosate. Therefore, tank-mixed application of glyphosate and carfentrazone may be beneficial than sole application to control broadleaf weeds.
Various combinations of glyphosate and 2,4-D (± surfactant) were evaluated for control of Brazil pusley [Richardia brasiliensis (Moq.) Gomez]. Typical 2,4-D symptoms on plants were manifested within 2 to 3 days after treatment. Application of glyphosate alone had only marginal effects (14%) on Brazil pusley, but the addition of Induce® (nonionic surfactant) significantly increased control to 83% and reduced the fresh weight by 68%. Application of Landmaster®II or a tank-mix of glyphosate + 2,4-D (± surfactants) resulted in 96% to 100% control. Treatment with 2,4-D alone, or with Induce®, or L-77® (organosilicone surfactant) resulted in 84%, 90%, or 100% control, respectively. Very low fresh weights of Brazil pusley were recorded when 2,4-D +Induce® or L-77®, Landmaster®II (± surfactants), or the tank-mix (± surfactants) were applied. In the regrowth studies, shoot weight was greater following application of glyphosate with or without L-77® or Kinetic® (a blend of nonionic and organosilicone) than following other treatments. The fresh weight of the shoots in the regrowth study, recorded following the application of 2,4-D or Landmaster®II (± surfactants), was very low except when Kinetic® was added to Landmaster®II. No regrowth of shoots occurred following the tank-mix treatment. Similar observations were recorded for roots. Plants treated with 2,4-D did not regrow. The presence of 2,4-D in either formulation accelerated synergistic effect of the glyphosate to the target site. Therefore, 2,4-D could be used either as a component of a formulation or in a tank-mix with glyphosate to control Brazil pusley. Chemical names used: N-(phosphonomethyl glycine) (glyphosate); 2,4-dicholorophenoxyacetic acid (2,4-D).
Abstract
Soil fumigations with Telone (1,3-dichloropropene and other chlorinated hydrocarbons) at the rates of 10, 20, and 30 gal/A and Nemagon (1,2-dibromo-3-chloropropane) at the rates of 1, 2, and 3 gal/A, one week before planting carrot and sweet corn seeds brought about significant increases in the content of total carotenes, β-carotene, and total sugars in carrots and the total carotenoids in sweet corn seeds and decreases in respiratory rates of the carrot roots.
Cultivated plants and their wild progenitors show marked phenotypic differences regarding seed dormancy, the ability to disperse seeds, growth habit, phenology, photoperiod sensitivity, etc. We have used RFLP mapping to investigate the genetic control of these differences in a recombinant inbred population derived from across between a snap bean and a wild bean. Traits were scored either at Davis or in Colombia. Our results suggest that the genetic control is relatively simple. In particular, most of the phenotypic variation (>60%) in the population could be accounted for in genetic terms for all but two traits. The genetic control of many traits involved genes with major effect (>30%). Some regions of the genome had major effects on several traits. Our results suggest that evolution can proceed by macromutations, domestication could have taken place fairly rapidly and introgression of additional genetic diversity could be itrogressed relatively easily from wild beans into the cultivated bean gene pool.
Abstract
The results of 2 years’ field trials indicate that application to the soil of s-triazines, including simazine, propazine, igran, and ametryne, at low concentrations (0.125 and 0.5 lb./A) increased the protein content of pea (Pisum sativum L., cv. Perfected Freezer) seeds. Relatively higher concentrations (1 and 4 lb./A) of simazine, atrazine, prometone, igran, or ametryne were needed to increase the protein content of sweet corn (Zea mays L., cv. Iochief) seeds. Both quantitative and qualitative changes were noted in the pattern of amino acids in the seeds from the treated plants.
Herbicides are usually applied multiple times by growers for season long weed control in Florida citrus (Citrus sp.). Rimsulfuron, a sulfonylurea herbicide has been recently registered for control of certain grasses and broadleaf weeds in citrus. To increase the weed control spectrum and reduce application cost, citrus growers often prefer to tank mix herbicides. Field experiments were conducted in 2010 and 2011 in citrus groves in central Florida to evaluate weed control efficacy and crop safety of rimsulfuron applied alone or in tank mixes with flumioxazin, pendimethalin, or oryzalin. Herbicides were applied sequentially in spring and fall in both years on the same experimental plot. Results suggested that rimsulfuron applied alone controlled >80% broadleaf and grass weeds up to 30 days after treatment (DAT) and was comparable to tank mixing rimsulfuron with pendimethalin or oryzalin; however, control was reduced beyond 30 DAT. Rimsulfuron tank mixed with flumioxazin was the most effective treatment at 30 and 60 DAT that provided, respectively, ≥88% and >75%, control of broadleaf weeds including brazil pusley (Richardia brasiliensis), dog fennel (Eupatorium capillifolium), common ragweed (Ambrosia artemisiifolia), cotton weed (Froelichia floridana), and virginia pepperweed (Virginia virginicum) compared with other treatments. Control of natalgrass (Melinis repens) was higher in all tank mix treatments compared with rimsulfuron applied alone with no difference among tank mix partners. Rimsulfuron tank mixed with pendimethalin or oryzalin had no advantage over rimsulfuron applied alone for control of broadleaf weeds. Among sequential applications, weed control was better after fall herbicide application (August) compared with spring (April) because of residual activity of fall applied herbicides. Rimsulfuron tank mixed with flumioxazin will provide citrus growers with an additional weed control option.
The ability of hairy vetch (Vicia villosa Roth) residue (100 g/plant) to supply N and to increase yields of tomato (Lycopersicon esculentum Mill.) was compared with that of N fertilization (0, 4.1, and 8.2 g/plant N) in a medium containing a mixture of 3 perlite: 1 vermiculite in a greenhouse and a lathhouse. Hairy vetch residue did not interact with N fertilization in affecting tomato yield and medium N concentration. In the greenhouse, leaf dry weight, leaf and stem N uptake, total (fruit + stem + leaf + root) dry weight and N uptake of tomato, and NH4 + and inorganic N concentrations in the medium at transplanting were significantly greater with than without residue. In the lathhouse, fruit number, fresh and dry yields and N uptake, leaf, stem, and root dry weights and N uptake, root length, total dry weight and N uptake of tomato, and NH4 +, NO3 -, and inorganic N concentrations in the medium at transplanting, and inorganic N at harvest were greater with than without residue. Nitrogen fertilization increased fruit number, fresh and dry yields and N uptake, stem, leaf, and root dry weights and N uptake, root length, and total dry weight and N uptake. The residue was as effective in increasing fresh fruit yield, total dry weight, and N uptake as was 4.4 to 7.9 g/plant of N fertilizer. Tomato yield and N uptake per unit amount of N supplied was greater for the residue than for N fertilization, suggesting that hairy vetch residue can be effectively used as N fertilizer for tomato production.
Our objective was to determine the effect of winter cover crops on the yield and N concentration of the following crop of tomato. No commercial fertilizer was applied to the tomato crop. Cover crops were planted in fall in a randomized complete-block design with control (fallow), rye, hairy vetch, and crimson clover treatments. `Mountain Pride' tomato was planted in spring after incorporating cover crops into the soil. Soil inorganic N content during the tomato growing season was significantly affected by the nature of cover crops planted during winter. Tomato planted after legumes had significantly greater amounts of inorganic N available for uptake compared to nonlegume or control. A rye cover crop did not have any effect on the yield of the ensuing tomato crop. On the contrary, a 15% increase in tomato fruit yields resulted from cover cropping with legumes. The N concentration in fruit in all treatments was similar. However, tomato grown after rye had significantly lower vegetative N concentration. Total N uptake was significantly greater in tomato succeeding legumes compared to nonlegume or fallow. It was concluded that by adding inorganic N into the soil, legumes increased the fruit yield and N uptake of the succeeding tomato crop.