The no-tillage system for peanuts (Arachis hypogaea L.) was investigated &om 1978 to 1981 in comparison with minimum and full tillage. Dficulty in controlling weeds, soil compaction, and reduced yields were problems associated with no-tillage peanut culture. No-tillage plots yielded 600 to 2400 kgha less than full tillage each year, while the minimum tillage plots were intermediate in yield. Peanut grades were not different except in 1980 when the no-tillage system graded less than full or minimum tillage. Disease due to southern blight (Sclerotiurn roKs$ was not aEected by tillage system except in 1980 when the full tillage plots produced a lower pod disease rating than minimum or no-tillage. Target hits were lower in the no-tillage plots than full tillage plots when averaged over the four year period.Key Words: Groundnut, no-tillage, minimum tillage, disease, yield, target sites.Minimum tillage and no-tillage have reduced production costs of corn, grain sorghum, and soybeans (1,6,10,11,13). However, very limited research has been reported with the use of these cultural practices in peanuts (Arachis hypogaea L.). If no-till were a viable alternative in peanut cultures, considerable savings in energy, machinery, and labor requirements could result in increased net returns for the peanut producer. No-tillage systems have not been considered feasible in peanuts due to potential problems of 1) severe disease infestations which can occur &om crop residue left on the soil surface, 2) weed competition due to poor control, especially for grass species prior to over the top herbicide availability, and 3) digging problems associated with weeds, crop residue, and soil compaction.The no-tillage system could be very useful in controlling soil erosion and conserving soil moisture. Its use in peanuts has been primarily confined to studies in Texas In comparison with conventional cultural practices, notillage reduced foliage, pod, and kernel yields by 58, 64, and 62 percent, respectively. Poor performance was attributed to at least two factors: 1) an inadequately prepared seed bed with a compacted zone immediately below and to the sides of the row which resulted in shallow planting, and 2) intense competition from grasses in the second half of the season which contributed to lower pod yields. Rajan et al. (14) conducted no-tillage research in India and found that no-tillage did not reduce the pod yield. He found that sandy loam soil facilitedeasy peg penetration and pod development, and higher soil moisture retention in the no-tillage accounted for no yield reduction. Surprisingly, in many instances southern blight has not become a severe problem in the no-tillage system.Hartzog and Adams (7) stated that elimination of deep tillage did not affect white mold hits. Colvin et al. (5) reported that in 1984 Sclerotium roLfsii occurred more frequently in conventional tillage plots than in the strip-tillage or no-tillage treatments while in 1985 disease occurrence was less in the no-tillage and conventional tillage plots.Pod...

CGA 82725 {2-propynyl [2-[4-[(3,5-dichloro-2-pyridinyl)oxy)] phenoxy] propanoate}, haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy]phenoxy] propanoic acid}, sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one}, and fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} were applied postemergence to Texas panicum (Panicum texanumBuckl. # PANTE), large crabgrass [Digitaria sanguinalis(L.) Scop. # DIGSA], and broadleaf signalgrass [Brachiaria platyphylla(Griseb.)Nash. # BRAPP] in peanut (Arachis hypogaeaL. ‘Florunner’). Fluazifop applied at 280 and 410 g ai/ha, sethoxydim at 340 g ai/ha, haloxyfop at 140 g ai/ha, and CGA 82725 at 280 g ai/ha usually gave better control when applied to annual grasses in the two- to four-leaf stage than when applied at the six- to eight-leaf stage. Higher rates of application were required to provide acceptable weed control at the later stage of growth. Peanut yields were usually higher following the early applications, indicating that timing of application is important in obtaining improved yields.

The herbicide 2,4-DB [4-(2,4-dichlorophenoxy) butyric acid] was not readily absorbed by peanut (Arachis hypogaea L.) leaves, was not accumlated in the nut at harvest and was very slowly metabolized to 2, 4-D (2,4-dichlorophenoxyacetic acid). In contrast, pigweed (Amaranthus retroflexus L.) readily absorbed the 2,4-DB and rapidly converted it to 2,4-D. The 2,4-D was subsequently translocated to the apical regions of the pigweed and resulted in severely reduced growth or death. Applications of 0.9 kg/ha of 2,4-DB between maximum pegging and early pod (fruit) enlargement reduced yield and affected quality and pod size. Repeated applications of 0.45 kg/ha of 2,4-DB did not adversely affect the peanut. An analytical procedure sensitive to 0.1 ppm of 2,4-D and 0.2 ppm of 2,4-DB is described for analysis of fresh plant forage and nuts.

When tank mixed with certain boadleaf-selective herbicides, fluazifop {(+)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid}, sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one}, haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid}, and fluazifop-P {(R)-2-[4-[[5-trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} were less effective in controlling two annual grasses, Texas panicum (Panicum texanumBuckl. #3PANTE) and large crabgrass [Digitaria sanguinalis(L.) Scop. # DIGSA]. These herbicides were applied alone or were combined with the broadleaf-selective herbicides bentazon {3-(1-methylethyl)-(1H)-2,l,3-benzothiadiazin-4(3H)-one-2,2-dioxide} and/or 2,4-DB [4-(2,4-dichlorophenoxy)butanoic acid]. The herbicide combinations controlled smooth pigweed (Amaranthus hybridusL. # AMACH) and yellow nutsedge (Cyperus esculentusL. #CYPES). Increasing the rates of the grass-selective herbicides in the mixture reduced the adverse effects of 2,4-DB or bentazon.

Eight breeding lines, three parents, and the cultivar Florunner were compared under two levels of disease pressure indbced by Sclerotium rolfsii Sacc., or Pythiurn rnyriotylurn Drechs. at each of two locations for three years to ascertain the effectiveness of the host plant resistance to each pathogen. Varied disease pressures were created by application of fungicides and supplement of fungal inoculum. Mean Florunner pod yields varied more than 1000 kg/ha as a result of the S. rolfsii treatments but the yields of the resistant TAG-3 were not affected. Disease incidence, as measured by frequency of S. rolfsi infection sites and diseased pods, was much higher for Florunner than TxAG-3. Breeding lines for which TxAG-3 was a parent sustained significant yield reductions. The disease incidence in these lines was higher than the resistant parent, equal or less than Tamnut 74, their other parent, and less than Florunner. The grades of TxAG-3 and its derivatives were lower than Florunner. Pod rot incidence differed for the P. rnyriotylurn treatments but pod yields were not different. TxAG-3 and Toalson sustained less pod disease than Florunner and Tamnut 74. The percent of diseased pod tissue for one derivative of Toalson was lower than Toalson and TxAG-3, and that of one TxAG-3 derivative was equal to its best parent. The breeding lines varied in reaction to the two diseases and some lines showed considerable resistance to both organisms.