Masters Theses

Date of Award

6-1985

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant, Soil and Environmental Sciences

Major Professor

David L. Coffey

Committee Members

L.S. Jeffery, Gilbert N. Rhodes Jr, Elmer L. Ashburn

Abstract

Field studies were conducted in 1983 and 1984 at The University of Tennessee Plant Science Farm, Knoxville, to evaluate the efficiency of overtop postemergence herbicide applications for weed control in conventional and no-tilled fresh market tomatoes [Lycopersicon esculentum (L.) 'Floradade']. The feasibility of growing fresh market tomatoes in no-tillage as compared to conventional tillage was also evaluated. Evaluations were determined on the basis of weed control ratings and fruit yields. In 1984 further investigations were made on early growth and nutrient uptake of plants between tillage systems.

The herbicide regime used for both conventional and no-tilled (wheat surface residue) systems in 1983 was a single application of metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4- triazin-5(4H)-one] at .56 kg ai/ha, a sequential application at the previous rate, fluazifop-butyl {(±)-butyl-2-[4-[[5-(trifluoromethyl)- 2-pyridinyl]oxy]phenoxy]propanate} at .28 kg ai/ha following metribuzin at the previous rate, and a weed free check. The broadleaf weed species present were tall [Ipomoea purpurea (L.)Roth], pitted (I. lacanosa L.) and ivyleaf [I. hederacea (L.)Jacq.] morningglory and prickly si da (sida spinosa L.). Annual grasses present were predominantly large crabgrass [Digitaria sanguinalis (L.)Scop.] and goosegrass [Eleusine indica (L. )Gaertn. ].

The single application of metribuzin controlled all broadleaf weeds as effectively as the other herbicide treatments within each tillage system. However, morningglories were better controlled by herbicides in conventional tillage than in no-tillage. The single application did not effectively control annual grasses in either tillage system. In both tillage systems the sequential application of metribuzin and the metribuzin followed by fluazifop-butyl gave equal annual grass control. Both treatments were better than the single application of metribuzin. Annual grasses were better con trolled by herbicides in no-till age than in conventional tillage. Marketable tomato fruit yields were higher in no-tillage plots receiving the sequential application of metribuzin and the fluazifopbutyl following metribuzin. Overall, marketable tomato fruit yields from no-tillage were nearly twice those from conventional tillage.

The herbicide regime for conventional tillage, no-till age (wheat residue), and no-tillage (vetch residue) in 1984 consisted of sequential applications of metribuzin at .37 kg ai/ha and .56 kg ai/ha followed by either sethoxydim {2-[1-(ethoxyimino)butyl]- (ethylthio)propyl]-3-hydroxy-2-cylohexen-1-one}, fluazifop-P-butyl, DPX-Y6202 {(±)-ethyl-2-[4-[(6-chloro-2- quinoxalinyl)oxy]phenoxy]propanate},or haloxyfop-methyl {(±)-methyl- 2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]propanate) at .28 kg ai/ha each. Weedy and weed free checks were also included. Broadleaf weed species present were redroot pigweed (Amaranthus retroflexus L.), common purslane (Portulaoa oleracea L.), and tall and pitted morningglory. The annual grasses present were large crabgrass, goosegrass, fall panicum (Panicum dichotomiflorum Michx.), and stinkgrass [Eragrostis cilianensis (All.)E. Mosher].

Sequential applications of metribuzin provided good control of broadleaf weeds. Sethoxydim, fluazifop-P-butyl, DPX-Y6202, and haloxyfop-methyl each gave excellent annual grass control. There were no differences in marketable fruit yields obtained from any of the treatments. Yields were higher in 1984 than 1983 due to more favorable growing conditions.

Early growth as reflected by stem height and diameter was greater from plants in no-tillage than from those in conventional tillage. Differences were also found in nutrient content of plant tissue among tillage systems. Plants from no-tilled areas were higher in phosphorus than those from the conventionally tilled areas. Plants grown in vetch residue had the highest levels of nitrogen and magnesium and the lowest levels of calcium and potassium, while plants grown in wheat residue had the highest level of potassium and the lowest levels of nitrogen and magnesium.

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