scholarly journals Biofumigation: A Cover Crop Option 12 Months of the Year to Manage Three Soilborne Pathogens Ailing the Australian Vegetable Industry

Author(s):  
J.D. Duff ◽  
M.C. Firrell

Brassica biofumigant cover crops are being increasingly considered in vegetable crop rotations as part of an integrated disease management strategy and simply as a cover cropping choice. Nine biofumigant varieties were assessed to see if they could be grown year-round in the Lockyer Valley South East Queensland region, for yield, days to incorporation and glucosinolate concentrations, as well as efficacy against 3 soilborne pathogens; Sclerotinia sclerotiorum, Sclerotium rolfsii and Macrophomina phaseolina. The fastest growing brassica biofumigant was BQ Mulch which reached 25% flowering in 36 and 59 days from planting to incorporation with a summer and winter planting respectively. Nemcon and Nemclear took the longest to incorporation when planted in summer, 101 days and failed to flower, while Caliente, Tillage Radish and Biofum reached 25% flowering and incorporation in 98 days when planted in winter. BQ Mulch produced the least amount of biomass, 30.93 t/ha fresh weight and 2.92 t/ha dry weight with a summer planting. Biofum producing the greatest amount of biomass, 185.76 t/ha fresh weight and 17.34 t/ha dry weight with a summer and winter planting respectively. Most varieties produced more total glucosinolates during summer compared to winter. Caliente produced the highest levels of Total GSLs with 53.47 µmol/g DW in summer compared to 23.78 µmol/g DW in winter. This was reflected in their efficacy against the soilborne pathogens. Caliente and Mustclean were more efficacious at controlling Macrophomina and Sclerotinia in summer compared to winter while all varieties were more efficacious at controlling Sclerotinia with a summer planting compared to a winter planting.

1988 ◽  
Vol 34 (3) ◽  
pp. 201-206 ◽  
Author(s):  
C. S. Rothrock ◽  
W. L. Hargrove

The influence of winter legume cover crops and of tillage on soil populations of fungal genera containing plant pathogenic species in the subsequent summer sorghum crop were examined in field studies. Legume cover crops significantly increased populations of Pythium spp. throughout the sorghum crop compared with a rye cover crop or no cover crop. This stimulation of the populations of Pythium spp. was not solely due to colonization of cover-crop residue, as populations were significantly greater at the time the legume cover crop was desiccated. Removal of aboveground residue generally decreased populations of Pythium spp. in soil. Incorporation of residue by tillage increased populations of Pythium spp. at some sampling dates. Legumes differed in the magnitude of stimulation, with hairy vetch stimulating Pythium spp. more than crimson clover. Cover crop treatments did not consistently influence soil populations of Fusarium spp., Rhizoctonia solani, Rhizoctonia-like binucleate fungi, or Macrophomina phaseolina. Macrophomina phaseolina populations were significantly greater under no tillage.


HortScience ◽  
2018 ◽  
Vol 53 (4) ◽  
pp. 432-440 ◽  
Author(s):  
Eric B. Brennan ◽  
Richard F. Smith

Strawberry (Fragaria ×ananassa Duch.) production in California uses plastic mulch–covered beds that provide many benefits such as moisture conservation and weed control. Unfortunately, the mulch can also cause environmental problems by increasing runoff and soil erosion and reducing groundwater recharge. Planting cover crops in bare furrows between the plastic cover beds can help minimize these problems. Furrow cover cropping was evaluated during two growing seasons in organic strawberries in Salinas, CA, using a mustard (Sinapis alba L.) cover crop planted at two seeding rates (1× and 3×). Mustard was planted in November or December after strawberry transplanting and it resulted in average densities per meter of furrow of 54 and 162 mustard plants for the 1× and 3× rates, respectively. The mustard was mowed in February before it shaded the strawberry plants. Increasing the seeding rate increased mustard shoot biomass and height, and reduced the concentration of P in the mustard shoots. Compared with furrows with no cover crop, cover-cropped furrows reduced weed biomass by 29% and 40% in the 1× and 3× seeding rates, respectively, although weeds still accounted for at least 28% of the furrow biomass in the cover-cropped furrows. These results show that growing mustard cover crops in furrows without irrigating the furrows worked well even during years with relatively minimal precipitation. We conclude that 1) mustard densities of ≈150 plants/m furrow will likely provide the most benefits due to greater biomass production, N scavenging, and weed suppression; 2) mowing was an effective way to kill the mustard; and 3) high seeding rates of mustard alone are insufficient to provide adequate weed suppression in strawberry furrows.


Weed Science ◽  
1996 ◽  
Vol 44 (3) ◽  
pp. 579-584 ◽  
Author(s):  
Melinda L. Hoffman ◽  
Leslie A. Weston ◽  
John C. Snyder ◽  
Emilie E. Regnier

Bioassays using binary mixtures that included a cover crop with known allelopathic potential and a weed species were employed to determine the importance of allelopathy compared to resource competition as interference mechanisms. Responses of weed species germinated with cover crops in a petri dish were measured. Interference between weed and cover crop seedlings was determined in a greenhouse experiment using the additive design, which included partitions to reduce above- and below-ground competition and used capillary mat subirrigation to control moisture and fertilizer availability. Germinating sorghum reduced radicle length of weeds, whereas germinating rye tended to increase weed radicle length. Methods limited above-ground competition, so likely interference mechanisms were below-ground competition and allelopathy. Germination with a cover crop had little effect on germination and shoot length of weeds. Increased density of rye but not of sorghum reduced growth of barnyardgrass seedlings. Reduced number of barnyardgrass leaves in the presence of rye was likely due to allelopathy. Suppression of barnyardgrass dry weight attributed to allelopathic interference by rye was successfully separated and compared to the combined effects of competition and allelopathy.


OENO One ◽  
2011 ◽  
Vol 45 (4) ◽  
pp. 223 ◽  
Author(s):  
Alícia Pou ◽  
Javier Gulías ◽  
Maria Moreno ◽  
Magdalena Tomàs ◽  
Hipolito Medrano ◽  
...  

<p style="text-align: justify;"><strong>Aims</strong>: In temperate climates, cover crops are mainly used to reduce excess soil water and nutrient availability to grapevines, which otherwise could decrease grape quality. In Mediterranean climates, where water is a limiting factor, the use of cover crops is not as straightforward. However, in this scenario, summer senescent and self-seeding herbaceous cover crops could also help to decrease soil erosion as well as to reduce excessive early vegetative vigour, which could restrict grape water availability at later phenological stages. The aim of this experiment was to study the effects of particular cover crops in Mediterranean vineyards on grapevine vegetative growth, gas exchange, yield and grape quality.</p><p style="text-align: justify;"><strong>Methods and results</strong>: The experiment was carried out over three consecutive years in an organic vineyard (cv. Manto Negro) in central Majorca, Spain. Three treatments (three cover cropping rows per treatment) were established: perennial grass and legume mixture (PM), no tillage, i.e., with permanent resident vegetation (NT), and traditional tillage or ploughed soil (TT). The grapevines were rain fed until veraison, and then drip irrigation was applied (30% potential evapotranspiration; ETP) until harvest. Plant water status was established according to a defined value of maximum daily leaf stomatal conductance (g<sub>s</sub>). Cover crops reduced total leaf area (LA), g<sub>s</sub> and grapevine vigour at early growth stages. g<sub>s</sub> and net photosynthesis (A<sub>N</sub>) were higher in cover crop treatments during the veraison and ripening stages, likely because of the reductions in LA. Intrinsic water use efficiency increased from flowering to veraison-maturity in all treatments. Yield was lower in the cover crop treatments (PM and NT) compared to TT for all years, but these differences were only significant in 2007. However, grape quality parameters slightly improved in the PM treatment.</p><p style="text-align: justify;"><strong>Conclusion</strong>: The use of cover crops decreased LA, helping to avoid dramatic reductions of stomatal conductance in mid-summer, but decreased yield and only slightly increased grape quality.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: This study showed that the use of specific cover crops in vineyards under Mediterranean climates helps to reduce vegetative vigour. Nevertheless, yield reduction and slight quality improvement suggest that cover crops should be adjusted in order to reduce competition for water and thus prevent these negative effects of water scarcity.</p>


2018 ◽  
Vol 64 (No. 2) ◽  
pp. 58-63 ◽  
Author(s):  
Patkowska Elżbieta ◽  
Jamiołkowska Agnieszka ◽  
Błażewicz-Woźniak Marzena

The present studies aim at determining the antagonistic effect of selected fungi species occurring in the soil under carrot cultivation towards Altenaria dauci (J.G. Kühn) J.W. Groves &amp; Skolko, Alternaria radicina Meier, Drechsler &amp; E.D. Eddy, Fusarium oxysporum E.F. Sm &amp; Swingle, Rhizoctonia solani J.G. Kühn and Sclerotinia sclerotiorum (Lib.) de Bary. The field experiment considered cover crops (oats, tansy phacelia and vetch). The control consisted of traditional carrot cultivation (without cover crops). Statistically, the smallest population of fungi was found in 1 g of soil dry weight after the application of oats, and a slightly bigger – after tansy phacelia and vetch. The largest population of fungi was obtained in the traditional cultivation of carrot. Cover crops contributed to the increase of the population of antagonistic Clonostachys spp., Myrothecium spp., Penicillium spp. and Trichoderma spp. in the soil. Regardless of the experimental treatment, those antagonistic fungi were the most effective in limiting the growth of S. sclerotiorum, A. dauci and A. radicina. The effect of those fungi was a little smaller towards F. oxysporum and R. solani. Oats as a cover crop had the best effect on the antagonistic activity of the studied fungi occurring in the soil environment of carrot.


Plant Disease ◽  
1997 ◽  
Vol 81 (5) ◽  
pp. 445-449 ◽  
Author(s):  
Gerard Rusuku ◽  
Robin A. Buruchara ◽  
Martin Gatabazi ◽  
Marcial A. Pastor-Corrales

The occurrence and distribution of soilborne fungi pathogenic to the common bean were determined by surveys conducted in seven of Rwanda's 10 prefectures during four growing seasons from 1989 to 1990. The pathogens were identified on the basis of symptoms, colony characteristics, reproductive structures, and pathogenicity tests. Of the plants sampled during the March through June 1989 season from four prefectures, 97% exhibited symptoms associated with soilborne pathogens. Root and hypocotyl symptoms appeared in plants sampled during the September through December 1989 season from the prefectures of Kigali (19%), Butare (40%), Gikongoro (33%), and Cyangugu (33%) and during the March through June 1990 season from Gisenyi (60%) and Kibungo (53%). Pythium spp., Macrophomina phaseolina, Rhizoctonia solani, and Fusarium oxysporum f. sp. phaseoli were isolated from all seven prefectures during all four seasons. Sclerotium rolfsii was isolated only during the 1990 September through December season. The frequency of isolation varied by region and season. Pythium spp. were the most frequently isolated fungi from about 40% of the samples, suggesting their potential importance in the root rot complex in Rwanda. The relative importance of the soilborne pathogens and possible relationships with existing cropping systems are discussed. These results will help focus efforts in developing management strategies for common bean diseases caused by soilborne pathogens in Rwanda.


2014 ◽  
Vol 30 (6) ◽  
pp. 550-562 ◽  
Author(s):  
S. O'Connell ◽  
J.M. Grossman ◽  
G.D. Hoyt ◽  
W. Shi ◽  
S. Bowen ◽  
...  

AbstractThe environmental benefits of cover cropping are widely recognized but there is a general consensus that adoption levels are still quite low among US farmers. A survey was developed and distributed to more than 200 farmers engaged in two sustainable farming organizations in NC and the surrounding region to determine their level of utilization, current practices and perceptions related to cover cropping. The majority of farms surveyed had diverse crop production, production areas <8 ha, and total gross farm incomes <US$50,000. Approximately one-third of the survey population had an organic production component. Eighty-nine percent of participants had a crop rotation plan and 79% of the total survey population utilized cover cropping. More than 25 different cool- and warm-season cover crops were reported. The statements that generated the strongest agreement about cover crop benefits were that cover crops: increase soil organic matter, decrease soil erosion, increase soil moisture, contribute nitrogen to subsequent cash crops, suppress weeds, provide beneficial insect habitat and break hard pans with their roots. Economic costs associated with cover cropping were not viewed as an obstacle to implementation. A factor analysis was conducted to identify underlying themes from a series of positive and negative statements about cover crops. Pre- and post-management challenges were able to explain the most variability (30%) among participant responses. Overall, participants indicated that the incorporation of residues was their greatest challenge and that a lack of equipment, especially for no-till systems, influenced their decisions about cover cropping. Farmers did not always appear to implement practices that would maximize potential benefits from cover crops.


HortScience ◽  
2007 ◽  
Vol 42 (2) ◽  
pp. 289-293 ◽  
Author(s):  
Michael J. Adler ◽  
Carlene A. Chase

The phytotoxicity of aqueous foliar extracts and ground dried residues of sunn hemp (Crotalaria juncea L.), cowpea [Vigna unguiculata (L.) Walp. cv. Iron Clay], and velvetbean [Mucuna deeringiana (Bort) Merr.] to crop and weed germination and growth was evaluated to compare the allelopathic potential of the cover crops. By 14 days after treatment (DAT), goosegrass [Eleusine indica (L.) Gaertn.] germination with 5% aqueous extracts of all cover crops (w/v fresh weight basis) was similar and greater than 75% of control. However, with the 10% extracts, goosegrass germination was lowest with cowpea extract, intermediate with velvetbean extract, and highest with sunn hemp extract. Livid amaranth (Amaranthus lividus L.) germination declined to ≈50% with cowpea and sunn hemp extracts and even lower to 22% with velvetbean extract. The suppression of livid amaranth germination was greater with the 10% extracts than the 5% extracts. Bell pepper (Capsicum annuum L.) germination was unaffected by velvetbean extract, inhibited more by the 5% cowpea extract than the 10% extract, and was also sensitive to the 10% sunn hemp extract. All cover crop extracts resulted in an initial delay in tomato (Lycopersicon esculentum Mill.) germination, but by 14 DAT, inhibition of germination was apparent only with cowpea extract. The phytotoxicity of ground dried residues of the three cover crops on germination, plant height, and dry weight of goosegrass, smooth amaranth (A. hybridus L.), bell pepper, and tomato was evaluated in greenhouse studies. Goosegrass germination was inhibited in a similar manner by residues of the three cover crops to 80% or less of control. Smooth amaranth germination, plant height, and dry biomass were more sensitive to sunn hemp residues than to cowpea and velvetbean residues. Bell pepper germination, plant height, and dry weight were greater than 90% of control except for dry weight with cowpea residue, which was only 78% of control. The greatest effect of cover crop residue on tomato occurred with dry weight, because dry weights with cowpea and sunn hemp were only 76% and 69% of control, respectively, and lower than with velvetbean. There was more evidence of cover crop phytotoxicity with the weed species than with the crop species and cowpea extracts and residue affected all species more consistently than those of sunn hemp and velvetbean.


2001 ◽  
Vol 11 (1) ◽  
pp. 150
Author(s):  
Mary C. Akemo ◽  
Mark A. Bennett ◽  
Emilie E. Regnier

Pure and biculture stands of rye `Wheeler' (Secale cereale L.) and field pea (Pisum sativum L.) were established and killed for mulch in Spring 1996, 1997, and 1998, in Columbus, Ohio. Treatments were five rye to pea proportions, each with a high, medium, and low seeding rate. Their effects on tomato (Lycopersicon esculentum Mill.) growth and yield were compared with those of a weedy check; a tilled, nonweeded check; and a tilled, hand-weeded check. Tomato tissue and soil were sampled for nutrient analysis. Number of leaves, branching, height, leaf area, dry weight, rate of flowering and fruit set, and fruit yield of tomato plants varied directly with the proportion of pea in the cover crop and decreased with reduced cover crop seeding rates. In 1997, yields of tomato were as high as 50 MT·ha-1 in the 1 rye: 3 pea cover crop; yield was poorest in the weedy check (0.02 MT·ha-1 in 1996). Most of the cover-cropped plots produced better yields than did the conventionally weeded check. No consistent relationship between levels of macronutrients in tomato leaf and soil samples and the cover crop treatments was established. Spring-sown rye + pea bicultures (with a higher ratio of pea) have a potential for use in tomato production.


HortScience ◽  
2000 ◽  
Vol 35 (5) ◽  
pp. 843-848 ◽  
Author(s):  
Mary C. Akemo ◽  
Mark A. Bennett ◽  
Emilie E. Regnier

Pure and biculture stands of rye `Wheeler' (Secale cereale L.) and field pea (Pisum sativum L.) were established and killed for mulch in Spring 1996, 1997, and 1998, in Columbus, Ohio. Treatments were five rye to pea proportions, each with a high, medium, and low seeding rate. Their effects on tomato (Lycopersicon esculentum Mill.) growth and yield were compared with those of a weedy check; a tilled, nonweeded check; and a tilled, hand-weeded check. Tomato tissue and soil were sampled for nutrient analysis. Number of leaves, branching, height, leaf area, dry weight, rate of flowering and fruit set, and fruit yield of tomato plants varied directly with the proportion of pea in the cover crop and decreased with reduced cover crop seeding rates. In 1997, yields of tomato were as high as 50 MT·ha–1 in the 1 rye: 3 pea cover crop; yield was poorest in the weedy check (0.02 MT·ha–1 in 1996). Most of the cover-cropped plots produced better yields than did the conventionally weeded check. No consistent relationship between levels of macro-nutrients in tomato leaf and soil samples and the cover crop treatments was established. Spring-sown rye + pea bicultures (with a higher ratio of pea) have a potential for use in tomato production.


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