Yield loss and management of downy mildew on field pea in Alberta,Canada

Downy mildew of field pea (Pisum sativum) caused by Peronospora viciae f. sp. pisi has become widespread in the main field pea production areas of central Alberta. Field experiments were conducted at naturally-infested field sites over several years to assess the effect of seeding depth, seeding date, seed treatment and foliar fungicides on downy mildew incidence and severity, and to estimate the relationship between severity and yield loss. Downy mildew was shown to cause substantial yield loss on field pea. Even a moderately severe infestation reduced pod numbers by 65% and seed yield by 75%. The loss (pod number or seed yield) was best explained by a linear model (y = −2.3114x + 10.086; R² = 0.9441 and y = −2.5165x + 10.378; R² = 0.9533, respectively). Depth of seeding (range 3–7 cm) did not affect downy mildew. Similarly, seeding date (early, mid and late May) did not have a consistent effect on disease levels. Late seeding occasionally reduced downy mildew, but always resulted in low seed yield. Several seed treatment fungicides reduced downy mildew, and metalaxyl-based products produced the highest yield. Several foliar-applied fungicides, including pyraclostrobin, azoxystrobin and metalaxyl, reduced downy mildew severity, but the results were not consistent across years. We conclude that cultural practices may not be sufficient for effective management of downy mildew, and that metalaxyl-based fungicides applied as seed treatments or foliar sprays could represent the best control option until downy mildew resistant pea cultivars become available.     

In vitro compatibility of microbial agents for simultaneous application to control strawberry powdery mildew (Podosphaera aphanis)

Biological control of plant pathogens on strawberries may be improved by the simultaneous application of different biological control agents (BCAs). Therefore, the compatibility of various BCAs which had previously shown to be effective against powdery mildew (Podosphaera aphanis (Wallr.) U. Braun & S. Takam) under laboratory conditions was examined in vitro. Inhibitory effects between fungal and bacterial BCAs were demonstrated in dual culture tests on two solid nutrient media. Leaf disc assays with single and multiple strain treatments demonstrated either unaffected or significantly improved control of P. aphanis for many multiple strain treatments, even if antagonistic interactions previously occurred in dual culture tests. Highest inhibition of powdery mildew conidiation (80.7% reduction) was achieved with multiple strain treatments with Bacillus subtilis FZB24 and Metarhizium anisopliae (p < 0.001). In this combination, conidiation was 3.7 times lower than in single treatments with B. subtilis indicating synergistic interactions between these BCAs. Combinations of Trichoderma harzianum T58 and B. subtilis FZB24 showed antagonistic interactions in dual culture tests as well as in leaf disc assays. In this combination, powdery mildew conidiation on leaf discs was four times higher compared to single treatments with T. harzianum T58.     

Bacillus megaterium A6 suppresses Sclerotinia sclerotiorum on oilseed rape in the field and promotes oilseed rape growth

Sclerotinia sclerotiorum causes serious yield losses in oilseed rape and other crops worldwide. Field trials were conducted at two locations to evaluate two formulations of oilseed rape seed containing the plant-growth promoting bacterium Bacillus megaterium A6 for suppression of this pathogen. Treatments containing strain A6 in pellet and in wrap formulations resulted in oilseed rape seed yields that were similar to the chemical control and significantly greater than the untreated seed control at both locations. Treatments containing A6 in pellet and wrap formulations also resulted in an incidence of disease caused by S. sclerotiorum that was similar to the chemical control. Both of these treatments significantly decreased disease incidence relative to the untreated seed control and to the respective formulated seed controls (that did not contain strain A6) at both locations. Strain A6 applied to oilseed rape seed in these two formulations promoted growth in greenhouse pot studies conducted with autoclaved soil. In two experiments, these treatments resulted in significant increases in mean shoot dry weight per pot and mean % total N per plant relative to their respective controls containing formulated oilseed rape seed without strain A6 and to the untreated seed control. Both formulations provided stable B. megaterium A6 (≥10⁶ CFU) and seed germination (>85%) over a six month period at room temperature. Experiments reported here indicate the commercial potential of these formulations of B. megaterium A6 for suppression of S. sclerotiorum on oilseed rape.     

Genetic resistance to and effect of leaf rust and powdery mildew on yield and its components in 50 soft red winter wheat cultivars

Effects of leaf rust (caused by Puccinia triticina f. sp. tritici Eriks.) and powdery mildew [caused by Blumeria graminis (DC.) E. O. Speer f. sp. tritici Em. Marchal], on performance of 50 soft red winter (SRW) wheat (Triticum aestivum L) cultivars were evaluated under natural field conditions. Widely grown cultivars released from 1919 to 2009 with varying disease resistance were grown in split-plot experiments in 2010 and 2011. Treated replications received seed treatments of triadimenol, captan and imidacloprid and foliar applications of propiconazole and prothioconazole + tebucanazole fungicides. Non-treated replications received only tebucanazole + metalaxyl + imazalil seed treatments. Final mean disease severity, agronomic, yield-related traits, yield components and spike characteristics were analyzed to determine individual and combined effects of leaf rust and powdery mildew on the cultivars. Yield losses as high as 54% were observed in the susceptible cultivar Red May. Average yield losses ranged from 1% to 21%. Yield losses primarily due to powdery mildew were as high as 14%, and losses primarily due to leaf rust were as high as 33%. Powdery mildew had the largest negative correlation with harvest index and seeds/spike. Leaf rust was most negatively correlated with plant biomass and harvest index, with a less consistent negative relationship with kernel weight.     

Control of Helminthosporium leaf blight of spring wheat using seed treatments and single foliar spray in Indo-Gangetic Plains of Nepal

Four fungicides for seed treatments and one as foliar spray were tested in replicated field experiments in a strip plot design to determine the effect of fungicides on Helminthosporium leaf blight (caused by Cochliobolus sativus and Pyrenophora tritici-repentis) severity and grain yield of wheat. Wheat seed cv. RR 21 was treated with fungicides, carbendazim (Areestin), triadimenol (Baytan), tebuconazole (Raxil), and carboxin + thiram (Vitavax 200B). Single foliar application of propiconazole (Tilt) was sprayed at flowering stage. Controls were included for both factors and treatments were replicated four times. Triadimenol and carboxin + thiram increased seed germination in both years. Triadimenol, tebuconazole, and carboxin + thiram reduced the number of infected seedlings and seedling root rot severity in both years. Number of tillers was higher in carboxin + thiram treated plots compared to other seed treatments. Compared to the control, carboxin + thiram increased grain yield by 9% and 8% in 2004 and 2005, respectively, and triadimenol by 6% in both years. The foliar spray of propiconazole significantly reduced Helminthosporium leaf blight severity and increased thousand-kernel weights. Propiconazole spray increased grain yield by 15% and 14% in 2004 and 2005, respectively. Therefore, seed treatment either with triadimenol or carboxin + thiram in combination with single post-flowering foliar spray of fungicides should minimize grain yield loss due to wheat foliar blight in South Asia. The findings of this study could be useful in developing strategies to manage Helminthosporium leaf blight in South Asia and other warm wheat growing regions of the world.     

Flea beetle (Phyllotreta undulata Kutschera) sensitivity to insecticides used in seed dressings and foliar sprays

Flea beetles of the genus Phyllotreta (Coleoptera: Chrysomelidae), which are severe pests in spring oilseed rape, have become increasingly difficult to control in some areas in Sweden. The current practice for plant protection is to use seed treatments followed by foliar applications of insecticide. Seed treatment with the single, currently registered neonicotinoid insecticide (active ingredient: imidacloprid) was compared to untreated controls and seed treatment with clothianidin using Phyllotreta undulata Kutschera beetles from 10 locations. Beetles from the overwintered generation and the new generation from the same 10 locations were used in bioassays to detect possible reduced sensitivity to the pyrethroid lambda-cyhalothrin. Seed treatment with clothianidin provided better protection for seedlings than imidacloprid. Highly variable results were obtained from the pyrethroid bioassays, but tests performed on beetles collected in August indicated that most sampled beetle populations are still susceptible to lambda-cyhalothrin. It is, however, important that the need for foliar applications is minimized to avoid insecticide resistance selection pressure. This requires seed treatments with adequate efficacy against flea beetles together with cultural control measures that can reduce flea beetle damage.     

Evaluation of systemic acquired resistance inducers for control of downy mildew on basil

Basil downy mildew, caused by Peronospora belbahrii Thines sp. nov., is a devastating foliar disease of fresh-cut basil first discovered in the U.S. in South Florida in 2007. Since then the pathogen has been found in over 20 U.S. states and has become a major threat to sweet basil production. In this study, acibenzolar-S-methyl (ASM, Actigard 50WG), DL-3-aminobutyric acid (BABA), isonicotinic acid (INA), salicylic acid (SA) and sodium salicylate (SS) were evaluated for their potential to control basil downy mildew in the greenhouse. Efficacy of these systemic acquired resistance (SAR) inducers varied in control of basil downy mildew depending on the rate, method and timing of application. Foliar sprays of ASM applied pre-, post- or pre- + post-inoculation at rates ranging from 25 to 400 mg l⁻¹ significantly (P = 0.05) reduced disease severity compared to the non-treated control in all experiments. ASM sprayed at 50 mg l⁻¹ three times on a weekly basis starting 3 and 7 days post- inoculation resulted in a 93.8 and 47.1% reduction in disease severity, respectively. Six weekly foliar sprays of BABA as pre- + post-inoculation at rates equal or higher than 125 mg l⁻¹ significantly suppressed downy mildew compared to the non-treated control. Foliar treatments of ASM or BABA followed by one or two post-inoculation sprays of a mixture of potassium phosphite (Prophyt) and azoxystrobin (Quadris) significantly improved efficacy for disease control. Sporangia counted on ASM treated leaves were significantly lower than leaves sampled from the non-treated control. ASM and BABA at concentrations lower than 1.0 mM did not inhibit sporangial germination in vitro. The effect of INA, SA and SS on disease reduction was generally inconsistent and not significant compared to the non-treated control.     

Emergence of cuphea seeds treated with different fungicides

Cuphea (Cuphea viscosissima Jacq. × C. lanceolata f. silenoides W.T. Aiton, Lythraceae) is an oilseed crop, with medium-chain fatty acids, being developed for the North Central United States for industrial applications in the manufacture of soaps and detergents. Seed germination and seedling emergence of cuphea is often low when compared to the commercial crops. Identification of seed treatments to optimize seedling emergence and stand establishment for cuphea are important for commercial production. The objective of this study was to determine the effect of several fungicide treatments on pure live seed emergence (PLSE) of cuphea. Pure live seed emergence is defined as total seedling emergence adjusted by the germination of the seed planted. Field experiments were conducted at Prosper, ND and Glyndon, MN, in 2005 and 2006. Previous crop rotations were soybean [Glycine max (L.) Merr.]/hard red spring wheat (Triticum aestivum L.), and soybean/hard red spring wheat/sugarbeet (Beta vulgaris var. saccharifera L.) at Prosper and Glyndon, respectively, for both years. The experimental design was a randomized complete block with six treatments and four replicates. Treatments were: no fungicide applied (check treatment), captan, mefenoxam, fludioxonil + mefenoxam, azoxystrobin, and azoxystrobin + mefenoxam. Plant stand was counted and PLSE was calculated 10 to 15 d after seeding at all locations by counting emerged seedlings in the center two-plot-rows and adjusting PLSE for germination. Greenhouse experiments were conducted with soil treatments (pasteurized and non-pasteurized) and the same fungicide seed treatments as the field experiment. Pure live seed emergence, vigor index, and percent of diseased seedlings were recorded. Plant stand and PLSE were significantly greater for the seed treatments that had mefenoxam at the Glyndon, MN, environments, in which the previous crop was sugarbeet. Soil treatment (pasteurization) increased PLSE and vigor index. All fungicide seed treatments improved PLSE and vigor index and reduced damping-off compared to the untreated check. Results suggest that seed treatments including mefenoxam would be beneficial for commercial cuphea production.     

Evaluation of bio-control agents for management of dry root rot of chickpea caused by Macrophomina phaseolina

Dry root rot of chickpea caused by Macrophomina phaseolina is an important disease affecting chickpea production areas in India, the largest producer of this crop in the world. The disease is primarily controlled through the use of fungicidal seed treatments. In this study, several isolates of two bio-control agents, Trichoderma viride and Pseudomonas fluorescens, were assessed for their ability to reduce the growth of M. phaseolina under laboratory conditions and subsequently used for field studies. The most effective isolate of each bio-control agent and the commonly used chemical seed-treatments, carbendazim and hexaconazole were evaluated. In addition to the use of the fungicides and bio-control agents individually as seed treatments, the study also included a trial combining soil application through bio-agent enriched farm-yard manure, along with seed treated with the bio-control agent. It was found that this combination showed maximum germination, least root rot incidence and highest yields as compared to the other biological or chemical seed treatments included in this study. This paper reports the identification of native isolates of T. viride and P. fluorescens that can be used under field conditions to control dry root rot of chickpea in tropical regions and demonstrates the use of a method of application that could significantly improve the efficacy of disease control while using bio-control agents.     

Integrated management of major diseases of mungbean by seed treatment and foliar application of insecticide,fungicides and bioagent

Field experiments were conducted during the rainy seasons of 2009 and 2010 for the management of the major diseases of mungbean, namely, wet root rot (Rhizoctonia solani), cercospora leaf spots (Cercospora canescens and Pseudocercospora cruenta) and yellow mosaic (Mungbean Yellow Mosaic Virus) by using different combinations of an insecticide, fungicide, and bio-formulation as seed treatment, with or without foliar sprays. A combination of seed treatment with thiamethoxam (Cruiser™) at 4 g kg⁻¹, carboxin (Vitavax™) at 2 g kg⁻¹ and Pusa 5SD (Trichoderma virens) at 4 g kg⁻¹ followed by simultaneous foliar sprays of thiamethoxam (Actara™) 0.02% and carbendazim (Bavistin™) 0.05% at 21 and 35 days after sowing resulted in the highest seed germination and grain yield in mungbean with the lowest intensities of cercospora leaf spots and mungbean yellow mosaic, and moderate incidence of wet root rot. The lowest whitefly population was also observed in this treatment during all stages of the crop. The treatment combinations having Pusa 5SD as seed treatment provided the lowest wet root rot incidence. Two sprays were superior to single spray for all variables recorded, but in combination with seed treatment, single spray was found to be more cost effective as it obtained the highest return per rupee of input. Use of T. virens based bio-formulation Pusa 5SD with insecticide thiamethoxam has been effectively demonstrated for the first time along with fungicides Bavistin and Vitavax for the management of the major diseases of mungbean.     

Trichoderma harzianum seed treatment controls Fusarium verticillioides colonization and fumonisin contamination in maize under field conditions

In northern Italy, the most frequently occurring class of mycotoxins in maize are fumonisins, mainly those produced by Fusarium verticillioides. Currently, good agricultural practices (GAPs) represent the best line of defense for controlling the contamination of maize by Fusarium-toxins. Annual fluctuations in weather conditions can strongly reduce the advantages conferred by GAPs, and thus integration with biological control strategies can be a sustainable way to achieve reliable control of Fusarium colonization and toxin contamination. Trichoderma harzianum is a good biocontrol agent against a wide range of plant pathogens, and previous studies have reported its ability to reduce F. verticillioides colonization under greenhouse conditions. Field trials were conducted in two locations to assess the effect of seed treatment with T. harzianum strain T22 on F. verticillioides kernel colonization and on fumonisin contamination under various natural conditions. An average reduction of 58% in fungal infestation and 53% in mycotoxin contamination was observed during our three-year experiments. This research suggests that seed biopriming with T. harzianum T22 can be a promising and environmentally friendly way to control F. verticillioides kernel colonization and fumonisin accumulation.     

Agronomic and economic assessment of intensive pest management of dry bean (Phaseolus vulgaris)

Two common production constraints of dry bean (Phaseolus vulgaris) in Ontario are annual weeds and anthracnose (caused by Colletotrichum lindemuthianum). Dry bean is not considered a competitive crop and weed interference can result in substantial yield losses, while anthracnose is considered one of the most devastating diseases in dry bean production. A study conducted in Ontario Canada, examined the effect of two herbicide programs on weed management, thiamethoxam insecticide treatment on plant enhancement and three fungicide programs on anthracnose development in a navy bean cv. ‘OAC Rex’. The premium herbicide program (s-metolachlor + imazethapyr) reduced percent weed ground cover relative to the economic herbicide program (trifluralin) in five of six locations. Thiamethoxam increased emergence and vigour at only one location, which contradicts reported benefits of thiamethoxam on plant health. The herbicide or thiamethoxam treatments did not affect anthracnose disease severity, visible seed quality, net yield or economic return. The fungicide seed treatment was often superior to the untreated control, for a number of the parameters measured. The application date of the foliar fungicide, relative to the onset of disease, varied between site-years. This dramatically influenced the fungicide’s effectiveness. Foliar fungicides increased seed quality and net economic return compared to the control when applied prior to disease development. The combination of fungicide seed treatment followed by a foliar fungicide provided the largest reduction in anthracnose severity.     

Potassium phosphite for control of downy mildew of soybean

Downy mildew of soybean, caused by Peronospora manshurica, is widely spread throughout Brazil. The objective of this study was to evaluate the use of potassium phosphite to control this disease. Field experiments were conducted during the growing season of 2006/2007 and 2007/2008 in the state of Parana in southern Brazil. The experimental design consisted of completely randomized blocks in a factorial arrangement (4 × 2) with four replications. Four rates of potassium phosphite (0, 375, 750 and 1500 g P₂O₅ + K₂O ha⁻¹) were applied at two growth stages, V6 (fifth trifoliolate leaf) and R2 (full flowering), followed by one or two applications of pyraclostrobin and epoxiconazole (66.5 + 25 g a.i. ha⁻¹) at R3 (pod development) or R2 and R5.1 (10% of pod filling), mainly for the control of Asian soybean rust (Phakopsora pachyrhizi) and powdery mildew (Microsphaera diffusa). Field experiments were conducted to quantify the severity of downy mildew on leaves, nutrient content in leaf tissue (N, P and K), leaf area index (LAI), yield and seed weight. The maximum severity of downy mildew was observed at a growth stage of R5.3 (50% of pods were ripe), with 14% and 46% of the leaf area affected in 2006/2007 and 2007/2008, respectively. Also it was detected some effect of phosphite on Asian rust control but it was mostly in the trial of 2007/08 when the epidemic was very low (9.7-21.8% of severity). There was a linear reduction in the severity of downy mildew and a significant improvement in the LAI with an increase in the rate of phosphite applied. During the 2006/2007 growing season, a significant yield improvement was observed due to the application of the highest rate of phosphite. Two fungicide applications following phosphite application significantly improved the control of Asian soybean rust and powdery mildew, yield and seed weight when compared to a single fungicide application.     

Efficacy of plant extracts and biocontrol agents against Pythium aphanidermatum inciting chilli damping-off

The fungitoxic effects of 66 medicinal plants belonging to different families were evaluated in vitro on Pythium aphanidermatum, the causal agent of chilli damping-off. Of these, Zimmu leaf extract (Allium sativum L. × Allium cepa L.) showed the highest inhibition of mycelial growth of P. aphanidermatum (13.7 mm). The antimicrobial compounds were isolated from Zimmu leaf extract and 22 compounds were identified through gas chromatography mass spectroscopy (GC–MS). Biocontrol agents Trichoderma viride and Pseudomonas fluorescens and Zimmu extract were also tested alone and together in vitro and in vivo experiments for control of P. aphanidermatum. The in vitro studies revealed that combination of T. viride + P. fluorescens + Zimmu leaf extract showed the highest mycelial growth inhibition over the control. Both antagonists were compatible with each other and with Zimmu leaf extract. The pot culture studies revealed that seed treatment with combined application of T. viride + P. fluorescens + Zimmu leaf extract was superior in reducing the pre and post-emergence damping-off incidence (8.3 and 17.0%, respectively), and increased the plant growth and yield (shoot length and root length of 13.7 and 6.3 cm, 146 g/plant, respectively) of chilli when compared to control.     

Persistence of an oilseed rape transgene in the environment

Transgenic bromoxynil (BX)-resistant spring oilseed rape (Brassica napus L.) was grown commercially in Canada only for two crop seasons – 2000 and 2001. We investigated the persistence of suspected BX-resistant oilseed rape volunteers in a 64-ha wheat field in Saskatchewan, Canada in 2007, 7 years after the BX-resistant cultivar BX Armor was grown. A small oilseed rape volunteer population, estimated at less than 100 plants, was observed in three main areas or patches in the field. These patches were located in low-lying areas that were too wet to plant or spray with herbicides in 2007. Viable seed was collected from 35 mature volunteers and F₁ progeny screened with BX at 280 g ai/ha in the greenhouse. Progeny of all of the volunteers were visually rated as BX-resistant; the presence of the Oxy 235 transgene in leaf tissue of progeny of all volunteers was confirmed by PCR analysis. This study has documented the longest persistence of oilseed rape volunteers in Canada. Volunteers were not observed in 2008 or 2009, because of drought conditions in spring of both years. Results support the findings from previous studies that persistence of volunteer oilseed rape populations in western Canada is generally ephemeral or transitory in the absence of seed bank immigration. However, this study shows that oilseed rape transgenes can persist in the environment for a number of years even after all cultivars with the conferred trait are removed from the market.     

Use of glufosinate-ammonium to control cruciferous weed species in glufosinate-resistant winter oilseed rape

Weed control is an important component of integrated cropping systems. However, cruciferous weeds are difficult to control in conventional winter oilseed rape (Brassica napus L.) and new herbicide options are needed. The aim of this study was to determine the potential for use of glufosinate-ammonium (2-amino-4-(hydroxymethyl-phosphinyl)-butanoic acid) as a flexible post-emergence herbicide for control of cruciferous weeds in glufosinate-resistant winter oilseed rape in the Hercynian dry region of Central Germany. The effects of glufosinate-ammonium (900 g active ingredients ha⁻¹) on chlorophyll fluorescence and dry matter in 4-week-old Sisymbrium loeselii L. (tall hedge mustard), S. officinale (L.) Scop. (hedge mustard), S. altissimum L. (tall tumble mustard), and Descurainia sophia (L.) Webb ex Prantl (flixweed) were assessed under controlled conditions in a growth room. A 2-year field trial was used to investigate the effect of glufosinate-ammonium on the dry matter of S. loeselii. Therefore, different application times (two- to four-leaf stage, five- to six-leaf stage, end of vegetative period in autumn, beginning of vegetative period in spring) and herbicide rates (450 and 900 g a.i. ha⁻¹) were tested.Under controlled growth room conditions, plants of all four cruciferous weed species showed a gradual decrease in the quantum yield of photosystem II. The quantum yield was less than 20% of the control plants measured from 0 to 34 h after application. Dry matter production of all four species was reduced to less than 3% that of the untreated control 4 weeks after application. Under field conditions, dry matter production of S. loeselii varied in dependence on the environmental conditions and was 0–88% of the control plants. Under controlled and field conditions, the results indicate that glufosinate-ammonium is effective in post-emergence control of the tested cruciferous weeds in glufosinate-resistant winter oilseed rape. Under field conditions, weather and crop growth influenced herbicide effectiveness.     

Anti-nutritive constituents in oilseed crops from Italy

Eight different oilseed crops (Brassica carinata, Camelina sativa, Coriandrum sativum, Euphorbia lagascae, Lepidium sativum, Lesquerella fendleri, Madia sativa, Vernonia galamensis) grown in Italy were investigated regarding anti-nutritive compounds, such as glucosinolates, sinapine, inositol phosphates and condensed tannins, which can adversely affect the nutritional value of residues from the oilseed processing. In all seeds at least one anti-nutritive compound was found, which possibly could lower the nutritive value, but in most cases a real negative effect is not to be expected. The existence and the concentration of the different anti-nutritive components varied in the different seeds. Glucosinolates and sinapine were found only in seeds of B. carinata, L. sativum, C. sativa and L. fendleri, whereas condensed tannins and inositol phosphates appeared in all seeds. In the different seeds the amount ranged from 0.2 mg/g (L. fendleri) to 13.1 mg/g (L. sativum) for sinapine, from 0.4 mg/g (E. lagascae) to 19.6 mg/g (L. fendleri) for condensed tannins, from 6.6 mg/g (E. lagascae) to 23.1 mg/g (B. carinata) for inositol hexa-phosphate as well as from 18.7 μmol/g (C. sativa) to 164.6 μmol/g (L. sativum) for glucosinolates.     

Effect of different soil tillage and organic fertilizers on winter triticale and spring barley stem base diseases

Multi-factor crop management field experiments were conducted in Vezaiciai, in southwestern Lithuania, from 2004 to 2006 to assess the influence of tillage and organic fertilizer management on stem base disease development. The treatments included 4-year crop rotations of continuous grass, winter triticale, winter oilseed rape and spring barley in combination with three tillage systems (shallow (8–10 cm) non-ploughing tillage, shallow (10–12 cm) tillage and deep (20–25 cm) ploughing). Eyespot prevailed both in winter triticale and spring barley crops. Winter triticale was more susceptible than spring barley. Shallow tillage decreased eyespot incidence and severity relative to deep tillage. Crop residue management exerted a weak but statistically significant effect on the disease development on triticale; in general, slightly higher numbers of affected stems were recorded in triticale plots where the straw from the previous crop had been removed prior to planting. However, complete straw removal from plots significantly decreased eyespot severity in comparison with crop residue or manure management treatments in spring barley. The highest number of affected triticale and barley plants was found in shallow (10–12 cm) tillage plots. The effects of residue management on minimising eyespot severity can be expected only after a delay of a few years.     

Herbicidal control of Solanum elaeagnifolium Cav. in Australia

Solanum elaeagnifolium Cav. is considered as one of the worst weeds of crop and pasture systems in temperate Australia. Effective long-term control is difficult due to the extensive root system. Field experiments were conducted at two locations in south-eastern Australia between 2006 and 2008 to examine a range of herbicides for control of S. elaeagnifolium on seed production and root regrowth. Herbicide performance was affected by herbicide, weed growth stage and environmental factors. Pyridine herbicides, such as pre-packed mixtures of aminopyralid + fluroxypyr and triclopyr + picloram + aminopyralid were the most effective and consistently reduced within-season aerial growth by 60–90% in both seasons. Overall control using glyphosate-based treatments was generally reduced due to emergence of new stems following herbicide application. Three picloram-based treatments provided the best and most consistent long-term control on root regrowth after two seasons, reducing stem emergence by 45–88%, especially with a late application of herbicides. The efficacy of residual herbicides such as atrazine or imazapic + imazapyr depends on rainfall conditions. Seedset control was best achieved with herbicides applied at the start of flowering stage, with no viable seed produced following treatments of 2,4-D amine + picloram and triclopyr + picloram + aminopyralid. These two treatments also significantly reduced viable seed production when applied at the early berry stage. The results indicate that an application at early flowering followed by a late application in autumn is necessary to effectively control the seedset (seedbank) and the root regrowth (rootbank) of S. elaeagnifolium.     

Interaction between seed treatments,surfactants and foliar fungicides on controlling dry bean anthracnose (Colletotrichum lindemuthianum)

Anthracnose, caused by fungal pathogen Colletotrichum lindemuthianum (Sacc. & Magnus) Briosi Cav. is one of the main production constraints of the dry bean (Phaseolus vulgaris L.) industry in Ontario. A field study was carried out in 2007 and 2008 to investigate the effect of two seed treatments (DCT (diazinon + captan + thiophanate-methyl) and MFA (metalaxyl-M + fludioxonil + azoxystrobin)) and two foliar fungicides (pyraclostrobin and azoxystrobin) applied with and without a surfactant under low and high disease pressure conditions at Exeter ON. Eighteen treatment combinations were tested in a randomized complete block design with four replicates. The treatment effects were examined by measuring disease development on leaf and pod tissue, pod destruction index, pick (discolored and misshaped seed), yield and return on investment (ROI). The seed treatment MFA performed similarly to DCT, and should be considered a suitable replacement to DCT for dry bean growers. However, utilizing a strobilurin fungicide in both seed and foliar treatments raises concern, as this practice increases the risk of disease resistance. The addition of a surfactant to azoxystrobin increased seed yield and ROI under high disease pressure, but had no effect when added to pyraclostrobin. Pyraclostrobin outperformed azoxystrobin for some disease indices as well as for yield under high disease pressure and for ROI under low and high disease pressure conditions.