Rapeseed Incorporation
Cohen, M. F., Yamasaki, H., and Mazzola, M. 2005. Brassica napus seed meal soil amendment modifies microbial community structure, nitric oxide production and incidence of Rhizoctonia root rot. Soil Biology & Biochemistry 37 (7):1215-1227. PDF
Abstract: A low glucosinolate content (21.8 micromoles/g) Brassica napus seed meal (RSM) applied to orchard soils altered communities of both pathogenic and saprophytic soil micro-organisms. RSM amendment reduced infection by native and introduced isolates of Rhizoctonia spp. and recovery of Pratylenchus spp. from apple roots. Root infection by Rhizoctonia solani AG-5 was also suppressed in split-root assays where a portion of the root system was cultivated in RSM-amended soils and the remainder grown in the presence of the pathogen but lacking RSM. R. solani hyphal growth was not inhibited by RSM amendment. Suppression of Pratylenchus was attained to an equivalent extent by amending soils with either RSM or soybean meal (SM) when applied to provide a similar N content. Thus, glucosinolate hydrolysis products did not appear to have a significant role in the suppression of Rhizoctonia spp. or Pratylenchus spp. obtained via RSM amendment. RSM amendment elevated populations of Pythium spp. and of ammonia-oxidizing bacteria that release nitric oxide but suppressed fluorescent pseudomonad numbers. Streptomyces spp. soil populations increased significantly in response to RSM but not SM amendment. The vast majority of Streptomyces spp. recovered from the apple rhizosphere produced nitric oxide and possessed a nitric oxide synthase homolog. We propose that transformations in the bacterial community structure are associated with the observed control of Rhizoctonia root rot, with NO production by soil bacteria potentially having a role in the induction of plant systemic resistance.
Link: http://cat.inist.fr/?aModele=afficheN&cpsidt=17163730
Broccoli Incorporation
Bhat, R. G., and Subbarao, K. V. 2001. Reaction of broccoli to isolates of Verticillium dahliae from various hosts. The American Phytopathological Society. 2001 Plant Dis. 85 (2):141-146.
Abstract: Isolates of Verticillium dahliae from 15 different hosts and V. albo-atrum from alfalfa were tested for their ability to cause wilt on broccoli using a root-dip inoculation method. None of the isolates caused vascular discoloration in broccoli except those from cabbage and cauliflower that were weakly pathogenic. Broccoli cultivars Baccus, Greenbelt, Parasol, Patriot, and Symphony showed resistance to Verticillium infection. Re-isolated strains from fresh samples of internally discolored broccoli and cauliflower root tissues were unable to cause disease symptoms on re-inoculation of broccoli, but caused severe disease on cauliflower. Inoculation of 5-, 7-, 9-, or 11-week-old plants did not alter the resistance in broccoli or the susceptibility in cauliflower against Verticillium. Immunity of broccoli against infection by isolates of V. dahliae from non-crucifer hosts, its resistance against crucifer isolates, and as previously described, attrition of V. dahliae microsclerotia in soil by broccoli residue, coupled with its importance as a commercial vegetable, make broccoli an attractive rotation crop for the management of Verticillium wilt in many cropping systems.
Link: http://www.apsnet.org/pd/pdfs/2000/1120-04R.pdf
Debode, J., Clewes, E., De Backer, G., and Hofte, M. 2005. Lignin is involved in the reduction of Verticillium dahliae var. longisporum inoculum in soil by crop residue incorporation. Soil Biology & Biochemistry 37 (2):301-309.PDF
Abstract: Verticillium wilt is an increasing problem in European cauliflower production. In this study, several crop residues were screened for their ability to reduce the viability of microsclerotia when incorporated into soil. In addition, the role of fungitoxic volatiles and lignin in the crop residue-mediated reduction in microsclerotia viability was studied. Broccoli (Brassica oleracea var. italica), cauliflower (B. oleracea var. botrytis), Indian mustard (Brassica juncea), ryegrass (Lolium perenne) and corn (Zea mays) were incorporated in naturally infested soil samples collected from two cauliflower fields in Belgium, labelled Is1 and S3. The effectiveness in reducing the viability of microsclerotia depended on the soil sample and on the type of residue. In the Is1 soil, broccoli, cauliflower and ryegrass incorporation significantly reduced the inoculum level by more than 90%, while Indian mustard significantly reduced numbers of viable microsclerotia by 50%. In the S3 soil, broccoli, cauliflower and Indian mustard were not effective, whereas ryegrass and corn incorporation reduced the microsclerotia level by 50% or more. In conclusion, incorporation of ryegrass and corn was more effective than incorporation of crucifer residues. In the conditions tested, fungicidal volatile compounds did not play an important role in Verticillium microsclerotia reduction in soil. Volatiles from broccoli and cauliflower did not affect microsclerotia viability in an in vitro bioassay, whereas the volatiles from Indian mustard killed the microsclerotia. Indian mustard incorporation in soil, however, only had a minor effect on microsclerotia viability. In the S3 soil, 1% (w/w) Kraft pine lignin, a waste product of the paper industry, had to be added to observe a significant reduction on the viability of microsclerotia, whereas in the Is1 soil, a significant effect was observed when 0.1% (w/w) Kraft pine lignin was added. Acid-insoluble lignin was extracted from all crop residues previously tested. Crop residues with high lignin content seemed to be more effective than crop residues with low lignin content. The reduction of Verticillium microsclerotia viability depended on lignin type and on crop structure, since lignin extracted from cauliflower leaves was more effective than lignin extracted from cauliflower stems and corn leaves were more effective than corn roots. Microsclerotia reduction was higher after fresh residue incorporation than after incorporation of their extracted acid-insoluble lignin, indicating that the effect of crop residue incorporation on microsclerotia viability cannot be explained solely by the effects of lignin. Incorporation of lignin-rich substrates in soil may open up new perspectives for integrated control of Verticillium.
Link: http://cat.inist.fr/?aModele=afficheN&cpsidt=16415986
Koike, S., and Subbarao, K. V. 2000. Broccoli Residues Can Control Verticillium Wilt of Cauliflower. Calif. Agric. 54 (3):30-33.PDF
Abstract: Verticillium wilt, a damaging
disease f cauliflower, was successfully managed in a multiple-year
field study by incorporating broccoli residues into infested soil. In
a study conducted from 1993 to 1995 in the Salinas Valley, cauliflower
disease incidence and severity were consistently and significantly reduced
in the broccoli residue plots when compared with no broccoli. The commercial
standard plots fumigated with methyl bromide + chloropicrin had the lowest
disease incidence and severity. In both years of our tarping study, Verticillium
wilt severity was lowest in the metham sodium treatment. The cauliflower-Verticillium
host-pathogen system therefore can act as a model for controlling soil-borne
diseases without the use of synthetic chemicals.
Link: http://californiaagriculture.ucop.edu/0003MJ/pdf/broccoli.pdf
Shetty, K. G., Subbarao, K. V., Huisman, O. C., and Hubbard, J. C. 2000. Mechanism of Broccoli-Mediated Verticillium Wilt Reduction in Cauliflower. Phytopathology. 90 (3):305-310.
Abstract: Broccoli is resistant to Verticillium dahliae infection and does not express wilt symptoms. Incorporation of broccoli residues reduces soil populations of V. dahliae. The effects of broccoli residue were tested on the colonization of roots by V. dahliae, plant growth response, and disease incidence of both broccoli and cauliflower in soils with different levels of V. dahliae inoculum and with or without fresh broccoli residue amendments. The three soils included a low-Verticillium soil, a high-Verticillium soil, and a broccoli-rotation soil (soil from a field after two broccoli crops) with an average of 13, 38, and below-detectable levels of microsclerotia per g of soil, respectively. Cauliflower plants in broccoli-amended high-Verticillium soil had significantly (P ≤ 0.05) lower wilt incidence and severity than did plants in unamended soil. An immunohistochemical staining assay utilizing a monoclonal antibody specific to V. dahliae was used to determine colonization of the root cortex. Despite the absence of wilt symptoms, broccoli roots were colonized by V. dahliae. In high-Verticillium soil, the broccoli residue amendment caused a marked reduction in colonization rate of V. dahliae per unit of inoculum on both cauliflower and broccoli roots. In addition to its detrimental effects on the viability of microsclerotia in soil, broccoli residue may also have an inhibitory effect on the root-colonizing potential of surviving microsclerotia.
Link: http://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO.2000.90.3.305
Subbarao, K. V., Hubbard, J. C., and Koike, S. T. 1999. Evaluation of Broccoli Residue Incorporation into Field Soil for Verticillium Wilt Control in Cauliflower. Plant Dis. 83 (2):124-129.
Abstract: Wilt incited by Verticillium dahliae has
recently become an important disease on cauliflower in the Salinas Valley.
Although broccoli is closely related to cauliflower, wilt has not occurred
on this host and V. dahliae isolates from cauliflower were weakly
pathogenic on broccoli in greenhouse inoculations. In this study, the
effectiveness of broccoli residues on propagule attrition in soil and
wilt incidence on cauliflower was determined in a commercial field infested
with V. dahliae microsclerotia. The treatments were broccoli
residue with tarp, broccoli residue without tarp, chloropicrin, metham
sodium, control with tarp, control without tarp, cauliflower followed
by cauliflower, and cauliflower followed by fallow. Approximately 200
kg of chopped broccoli was uniformly disk incorporated into the corresponding
plots (36 m2). Densities of V. dahliae microsclerotia were determined
at 0, 30, 90, and 145 days after treatment in 1993 and 0, 30, 74, 109,
and 140 days after treatment in 1994 using the modified Anderson sampler
technique. Cauliflower cultivar White Rock was planted in all plots. Plant
height, number of marketable heads, head weight, and wilt severity were
determined at maturity. Even though the pre-treatment number of V.
dahliae propagules in broccoli-treated and control plots were similar,
by the end of the cauliflower cropping season numbers either were the
same or increased in control plots compared with a reduction in numbers
in broccoli residue-treated plots during both seasons. There were no differences
between tarped and non-tarped plots either in broccoli residue-treated
or control plots. In fumigated plots, propagules declined initially but
later returned to pre-treatment levels by the end of the cropping season.
Continuous cauliflower or fallowing after one cauliflower crop resulted
in stable or increased levels of microsclerotia. Verticillium wilt severity
was lowest in metham sodium-treated plots, followed by broccoli residue-treated
plots and chloropicrin in both years. Plant height, marketable heads,
and head weight were higher in broccoli-
treated than in control plots. These results suggest that broccoli residues
reduce V. dahliae microsclerotia in soil and wilt of cauliflower
as much as or more than chloropicrin and metham sodium, and that rotation
with broccoli may be a feasible approach to manage Verticillium wilt in
cauliflower and other susceptible crops.
Link: http://apsjournals.apsnet.org/doi/pdf/10.1094/PDIS.1999.83.2.124
Xiao, C. L., Subbarao, K. V., Schulbach, K. F., and Koike, S. T. 1998. Effects of Crop Rotation and Irrigation on Verticillium dahliae Microsclerotia in Soil and Wilt in Cauliflower. Phytopathology 88 (10):1046-1055.
Abstract: Experiments were conducted in field plots to evaluate the effects of broccoli residue on population dynamics of Verticillium dahliae in soil and on Verticillium wilt development on cauliflower under furrow and subsurface-drip irrigation and three irrigation regimes in 1994 and 1995. Treatments were a factorial combination of three main plots (broccoli crop grown, harvested, and residue incorporated in V. dahliae-infested plots; no broccoli crop or residue in infested plots; and fumigated control plots), two subplots (furrow and subsurface-drip irrigation), and three sub-subplots (deficit, moderate, and excessive irrigation regimes) arranged in a split-split-plot design with three replications. Soil samples collected at various times were assayed for V. dahliae propagules using the modified Anderson sampler technique. Incidence and severity of Verticillium wilt on cauliflower were assessed at 7- to 10-day intervals beginning a month after cauliflower transplanting and continuing until harvest. Number of propagules in all broccoli plots declined significantly (P < 0.05) after residue incorporation and continued to decline throughout the cauliflower season. The overall reduction in the number of propagules after two broccoli crops was approximately 94%, in contrast to the fivefold increase in the number of propagules in infested main plots without broccoli after two cauliflower crops. Disease incidence and severity were both reduced approximately 50% (P < 0.05) in broccoli treatments compared with no broccoli treatments. Differences between furrow and subsurface drip irrigation were not significant, but incidence and severity were significantly (P < 0.05) lower in the deficit irrigation regime compared with the other two regimes. Abundance of microsclerotia of V. dahliae on cauliflower roots about 8 weeks after cauliflower harvest was significantly (P < 0.05) lower in treatments with broccoli compared with treatments without broccoli. Rotating broccoli with cauliflower and incorporating broccoli residues into the soils is a novel means of managing Verticillium wilt on cauliflower and perhaps on other susceptible crops. This practice would be successful regardless of the irrigation methods or regimes followed on the susceptible crops.
Link: http://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO.1998.88.10.1046
Mustard Incorporation
Alva. Ashok, Rick A. Boydston, and Harold Collins.
Mustard for Pest Control, Not for
your sandwich. Integrated Farming systems. Agricultural Research.
October 2004.
Abstract: Cover crops provide many benefits to producers including reduced soil erosion and compaction, increased soil tilth and water infiltration, and reduced incidence of pests and diseases. Research evaluating the cumulative effects of fall-planted cover crops including mustards, sorghum-sudangrass, an oat-hairy vetch mix, and wheat in a four-year crop rotation of potato-winter wheat-sweet corn-sweet corn is being conducted in Washington State. The response of weeds, nematodes, disease incidence, soil microbial communities, and nitrogen cycling is being evaluated. Seed meal of several mustard species suppressed chickweed and prickly lettuce germination and emergence and root knot nematodes in green house trials. Yields of potato, sweet corn and winter wheat following cover crops have been similar to that where fumigation and no cover crop was used.
Link: http://www.ars.usda.gov/is/AR/archive/oct04/pest1004.pdf