Yellow nutsedge (Cyperus esculentus L.) is a serious weed problem in the United States and other countries. An indigenous rust fungus [Puccinia canaliculata (Schw.) Lagerh.], pathogenic on yellow nutsedge, was released in early spring as a potential biological control agent. The fungus inhibited nutsedge flowering and new tuber formation. The fungus also dehydrated and killed nutsedge plants. The successful control of yellow nutsedge by a rust epiphytotic under experimental conditions demonstrates the potential use of the rust in an integrated weed management system.

Cultural and mechanical methods are viable options for inclusion in any weed control program. Selection of weed control methods is determined by crop, cost, desired yield, weather, and labor availability. Yellow and purple nutsedge (Cyperus esculentusL. # CYPES and C.rotundusL. # CYPRO) have proliferated as production inputs have intensified. Nutsedge densities have increased largely due to reduced competition as better annual weed control and improved growing conditions have resulted.

Alachlor, chloramben, cinmethylin, diphenamid, fluazifop, fluazifop-P, metolachlor, metribuzin, napropamide, oryzalin, and sethoxydim were applied on transplanted sweet potato at Tifton, GA, during 1982 to 1985. The weeds most prevalent were large crabgrass, Florida pusley, smallflower morningglory, and yellow nutsedge. No significant phytotoxicity was observed from any herbicide treatment over the 4 yr. Cultivation at 4 wk is advantageous to eliminate early flushes of weeds which escape control and reform the beds. Alachlor or metolachlor at 4.5 and 3.4 kg ha-1, respectively, and metribuzin controlled weeds best. Although no serious phytotoxicity was evident, these treatments tended to cause lowered yields of marketable roots while marginally affecting total yields in most cases. Metribuzin was the only compound which controlled late-season broadleaf weeds such as smallflower morningglory effectively.

and m long) were six replicates of four types Epperson, J. E. 1985. Effect of root diseases and nematodes on yield of corn in an irrigated of pest management for soil pests: multiple-cropping system with pest management. Plant Disease 69:382-387. 1. MBR-CP. Between 14 November and 8 February each year, soil was treated Corn was planted each of 6 yr in an annual multiple-cropping system of turnip-corn-cowpea with with 358.7 kg/ha MBR-CP (98% methyl four types of soil pest management. Treatments were 1) broadcast soil fumigation with 98% methyl bromide + 2% chloropicrin (MBR-CP) each fall or winter; 2) broadcast soil fumigation with 20% bromide + 2% chloropicrin) injected methyl isothiocyanate + 80% chlorinated C 3 hydrocarbons (DD-MENCS) each fall + maximum broadcast 25 cm deep with chisels 20 cm pest control with nonvolatile nematicides, herbicides, and insecticides; 3) nonvolatile nematicides, apart. The soil surface was shaped and herbicides, and insecticides used for an intermediate level of pest control; and 4) one herbicide and sealed with a bed-shaper attachment, and cultivation used as needed on each crop for a minimum level of weed control. Root diseases of corn the plots were covered with black polywere caused primarily by Pythium aphanidermatum, P. arrhenomanes, Rhizoctonia solani AG-4, a ethylene (152 /.tm thick) for 48 hr. No sterile white basidiomycete, and Phoma terrestris. Soil fumigation reduced root disease severity other soil pesticides were applied, and significantly in 5 of 6 yr and increased grain yield an average of 7.5% (0.94 t/ha). Populations of weeds were removed by hand in each crop. Meloidogyne spp., Paratrichodorus minor, and Pythium spp. and root disease severity ratings were 2. Maximum. Soil was fumigated correlated negatively with yield. between 14 November and 17 December Additional key words: intensive cropping, Macroposthonia ornata, Zea mays with 376.6 kg/ha DD-MENCS (20% methyl isothiocyanate + 80% chlorinated C3 hydrocarbons) using the methods Numerous fungi can be isolated from MATERIALS AND METHODS described for MBR-CP, except the plots roots of corn in the Georgia coastal plain, Corn (Zea mays L. 'Pioneer 3369A' or were not covered with plastic. Ethoprop and several are known pathogens 'Funks G-4507') was planted on Tifton granules (8.96 kg a.i./ha) were broadcast (11,21,22). Fungi have been associated loamy sand (fine loamy, siliceous, on the soil surface and incorporated 15 with seedling decline in sweet corn (26) Thermic Plinthic Palevdult; 85, 10, and cm deep with a tractor-driven rototiller and changes in mineral concentrations in 5% sand, silt, and clay, respectively; 0.5% before planting each crop in 1975 and tissue of field corn (11). Nematodes, organic matter) each year from 1975 to 1976. Nematicides were not applied from weeds, and insects also may reduce growth 1980 in an annual multiple-cropping 1977 through 1980 because they were not and yield of corn (9,10). Corn is grown in sequence of turnip (Brassica campestris needed. A maximum chemical pest numerous crop...

Sicklepod (Cassia obtusifoliaL. ♯ CASOB) was planted at six densities (0 to 39.4/m2) and six durations of competition (0 to 10 weeks after seeding) in lima beans (Phaseolus lunatusL. cv. ‘Jackson Wonder’). The yield of green lima beans was inversely proportional to the density of sicklepod. In general, weed densities at 2.7 to 10.8 sicklepod/m2did not significantly reduce yields, but higher populations frequently did. The average yields generally decreased if the duration of competition exceeded six weeks.