resource ( Masago et al., 1977 ; Meerow, 1994 ; Prasad, 1997 ). It has been demonstrated that coir can suppress certain soilborne plant pathogens ( Candole and Evans, 2004 ; van der Gaag and Wever, 2005 ). Combining the disease-suppressive properties of
Naveen Hyder, James J. Sims, and Stephen N. Wegulo
Cary L. Rivard and Frank J. Louws
Profitable heirloom tomato production is a major challenge in the southeast as a result of weathered soil structure, abiotic stress, and diseases caused by foliar and soilborne plant pathogens. Diseases caused by pathogens such as Fusarium
Jacqueline Joshua and Margaret T. Mmbaga
ranking fifth in production after Florida, Georgia, California, and New York ( USDA/NASS, 2015 ). Snap beans are susceptible to various major soilborne pathogens such as Pythium damping-off, wilt, and pod rot (various Pythium species), Rhizoctonia
Ramsey Sealy, Michael R. Evans, and Craig Rothrock
demonstrated to have antifungal properties against some soilborne fungi. Russell and Mussa (1977) found that a crude juice extract of crushed garlic cloves inhibited in vitro growth of Fusarium solani f.sp. phaseoli and provided adequate in vivo control
David Noshad, Andrew Riseman, and Zamir Punja
Plant Pathol. 48 320 324 Shew, H.D. Meyer, J.R. 1992 Thielaviopsis 171 174 Singleton L.L. Mihail J.D. Rush C.M. Methods for research on soilborne phytopathogenic fungi Amer
J.O. Kuti, G.V. Latigo, and J.O. Bradford
Soil-borne pathogens such as Macrophomina phaseolina (the causative agent of charcoal rot) and Phymatotrichum omnivorum (the causative agent of cotton root rot) contribute to mortality of transplanted guayule (Parthenium argentatum, Gray) seedlings in southern Texas. In order to select guayule genotypes for resistance to these pathogens, it would be useful to develop reliable greenhouse inoculation procedures for screening guayule seedlings. Twelve-week-old guayule seedlings (`11591', a USDA standard breeding line) were inoculated using two inoculation methods (soil-drenching and root-dipping) in two soil media (field soil and commercial soil mix). Plants were rated for disease severity 2 to 5 months after inoculation and pathogens were re-isolated from diseased plants to establish Koch postulates. The soil drenching technique, using field soil, caused rapid development of disease symptoms that were consistent with re-isolation frequencies of pathogens from the diseased plant tissues.
T.K. Hartz, P.R. Johnstone, E.M. Miyao, and R.M. Davis
Mustard (Brassica spp.) cover crop residue has been reported to have significant `biofumigant' action when incorporated into soil, potentially providing disease suppression and yield improvement for the succeeding crop. The effects of growing over-winter mustard cover crops preceding processing tomato (Lycopersicon escultentum Mill.) production were investigated in six field trials in the Sacramento Valley of California from 2002–04. A selection of mustard cover crops were compared to a legume cover crop mix, a fallow-bed treatment (the current grower practice in the region), and in two of the six trials, fumigation treatments using metam sodium. Mustard cover crops removed 115 to 350 kg·ha–1 N from the soil profile, reducing NO3-N leaching potential. Soil populations of Verticillium dahliae Kleb. and Fusarium spp. were unaffected by the cover crops, and there was no evidence of soilborne disease suppression on subsequent tomato crops. Mustard cover crops increased tomato yield in one field, and reduced yield in two fields. In one of two fields, metam sodium fumigation significantly increased tomato yield. We conclude that, while environmental benefits may be achieved, mustard cover cropping offers no immediate agronomic benefit for processing tomato production.
Ryan J. Hayes, German Sandoya, Beiquan Mou, Ivan Simko, and Krishna V. Subbarao
, designated RH14-1156, RH14-1157, and RH14-1158, are the first to combine resistance to the soilborne diseases corky root and verticillium wilt race 1. The populations are genetically fixed for disease resistance, and all progeny descending from these
James P. Gilreath, Timothy N. Motis, Bielinski M. Santos, Joseph W. Noling, Salvadore J. Locascio, and Daniel O. Chellemi
Field studies were conducted during four consecutive tomato (Lycopersicon esculentum) -cucumber (Cucumis sativus) rotations to examine the longterm residual effects of tomato methyl bromide (MBr) alternatives on soilborne pests in double-cropped cucumber. Four treatments were established in tomato fields: a) nontreated control; b) MBr + chloropicrin (Pic) (67:33 by weight) at a rate of 350 lb/acre; c) tank-mixed pebulate + napropamide at 4 and 2 lb/acre, respectively, followed by 1,3-dichloropropene (1,3-D) + Pic (83:17 by volume) at 40 gal/acre; and d) napropamide at 2 lb/acre followed by soil solarization for 7 to 8 weeks. Each of the following seasons, cucumber was planted in the same tomato plots without removing mulch films. For nutsedge [purple nutsedge (Cyperus rotundus) and yellow nutsedge (C. esculentus)] densities, napropamide followed by solarization plots had equal control (≤15 plants/m2) as MBr + Pic during all four cropping seasons. However, nematode control with solarization was inconsistent. Marketable yield data proved that fumigation in tomato fields with either MBr + Pic or pebulate + napropamide followed by 1,3-D + Pic had a long-term effect on double-cropped cucumber.
Richard Smith*, Krishna Subbarao, Steve Koike, Steve Fennimore, and Adelia Barber
Growers in the Salinas Valley are not able to rotate away from lettuce to other crops such as broccoli, as often as would be desirable due to economic pressures such as high land rents and lower economic returns for rotational crops. This aggravates problems with key soilborne diseases such as Sclerotinia minor, Lettuce Drop. Mustard cover crops (Brassica juncea and Sinapis alba) are short-season alternative rotational crops that are being examined in the Salinas Valley for the potential that they have to reduce soilborne disease and weeds. Mustard cover crops have been have been shown to suppress various soilborne diseases and there are also indications that they can provide limited control of some weed species. However, no studies have shown the impact of mustard cover crops under field conditions on S. minor. In 2003 we conducted preliminary studies on the incidence of S. minor and weeds following mustard cover crops in comparison with a bare control or an area cover cropped to Merced Rye (Secale cereale). There was a slight, but significant reduction of S. minor infection in one of three trials following mustard cover crops. Mustard cover crops also reduced emergence of Shepherd's Purse (Capsella bursa-pastoris) and Common Purslane (Portulaca oleracea) these studies. Mustard cover crops have distinct nitrogen cycling characteristics. They were shown to reach a peak of release of nitrogen in 30 to 50 days following incorporation into the soil. The levels of nitrogen that are released by mustard cover crops were substantial and could be useful in nitrogen fertilizer programs for subsequent vegetable crops.