Regulation of the Verticillium wilt Ve resistance genes in tomato plants. C. D. M. CASTROVERDE, L. G. M. DE ÁVILA, V. AMAYA, R. N. NAZAR AND E. J. ROBB. Department of Molecular and Cellular Biology, Summerlee Science Complex, College of Biological Science, University of Guelph, Guelph, ON N1G 2W1, Canada
Resistance to Verticillium wilt has been associated with the tomato Ve resistance genes. Endogenous expression of these two R-genes Ve1 and Ve2 are induced in ‘Craigella’ tomato plants infected with Verticillium dahiae Kleb. race 1 (Vd1). We found that induction is not limited to Vd1 but can also be observed in plants infected with other strains of V. dahliae, specifically Vd2 and Dvd-E6. Transcript levels are also induced in the absence of pathogen, through wounding in ‘Craigella’ as well as other cultivars. These observations raise the question of how biotic and abiotic stresses regulate Ve gene expression. In order to investigate this, we over-expressed the characterized Vd1 effector Ave1 in tomato plants. Preliminary results do not show any effect on Ve1 or Ve2 expression. To further dissect the elements responsible for Ve gene regulation, a promoter-reporter assay was designed using transgenic tomato plants. Deletion mutations of the upstream regions of Ve1 and Ve2 were fused to a reporter gene and transcriptional activity was assessed through RT-PCR. Initial data showed that the transcriptional activity of the Ve1 and Ve2 promoters were weak, agreeing with the basal Ve1/Ve2 mRNA levels. Interestingly, infection with Vd1 did not induce expression of the reporter gene. These preliminary results suggest that stresses contribute to the regulation of Ve1 and Ve2, but further analyses need to be done in order to determine the specific factors and elements responsible for this regulation.
Soil amendments for the management of Fusarium wilt in spinach. B. D. COLLINS, M. R. MCDONALD, L. J. DU TOIT AND S. WESTERVELD. Department of Plant Agriculture, Crop Science Building, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; (L.J.D.) Department of Plant Pathology, Washington State University Mount Vernon, 16650 State Route 536, Mount Vernon, WA 98273, USA; and (S.W.) Ontario Ministry of Agriculture, Food and Rural Affairs, 1283 Blueline Road, Simcoe, ON N3Y 4N5, Canada
Fusarium wilt, caused by the soilborne pathogen Fusarium oxysporum f. sp. spinaciae (Sherb.) Snyd. & Hans, is a destructive and persistent disease in spinach production. Field trials were conducted in July and August of 2013 and 2014 in naturally infested soils in Hamilton, Ontario. Disease severity and vascular discolouration were assessed 6 weeks after seeding. In 2013, Basamid (dazomet), Busan 1236 (metam sodium), Perlka (calcium cyanamide), Mustgrow (Brassica juncea (L.) Czern.) and a high nitrogen treatment (200 kg N ha−1) were applied 6 weeks before seeding. Disease pressure was low in 2013 with the untreated check having a maximum disease incidence of 11.5%. All treatments reduced disease severity compared with the untreated check. In 2014, the highly susceptible spinach cultivar ‘Norgreen’ replaced the cultivar ‘Greyhound’ used in 2013. A Pic-Plus (chloropicrin) and compost application (75 t ha−1) were evaluated in addition to the treatments used in 2013. Spinach in plots treated with Perlka (calcium cyanamide) and compost (75 t ha−1) had 13.3% and 14.6% wilt severity, respectively, which did not differ from wilt severity in control plots (14.1%). Application of MustGrow increased Fusarium wilt severity to 24.7%. Busan 1236 and a high nitrogen treatment reduced disease severity to 7.2 and 6.3%, while Basamid and Pic-Plus reduced disease severity to 3.1 and 1.0%, respectively. The population of F. oxysporum in soil was reduced by pre-plant applications of Busan 1236, Basamid and Pic-Plus to 162, 75 and 0 CFU g−1 soil, respectively, compared with 9750 CFU g−1 in control plots. Soil amendments can be effective tools in managing Fusarium wilt in spinach.
Environmental parameters influencing clubroot incidence and severity on canola. T. J. CRANMER, B. D. GOSSEN AND M. R. MCDONALD. Department of Plant Agriculture, Crop Science Building, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada; and (B.D.G.) Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
Canola (Brassica napus L.) is a major crop in Canada with an economic value of over $19 billion per year. Plasmodiophora brassicae Woronin, the causative agent of clubroot, can cause substantial decreases in yield of susceptible crucifer species. The objective of this study was to assess the effects of temperature and soil moisture on the incidence and severity of clubroot by seeding canola at multiple dates throughout the growing season. Canola was seeded in soils naturally infested with pathotype 6 of P. brassicae approximately every 2 weeks in 2013 and 2014, and 50 plants per experimental unit were assessed at 2-week intervals starting 4 weeks after seeding. Clubroot symptoms at 6 weeks after seeding were correlated with certain weather events and environmental conditions. Soil moisture at 5–15 days after seeding (r = 0.89) and rainfall at 3 weeks before harvest (r = 0.74) were correlated with clubroot severity. Air temperature during the first 2 weeks after seeding was correlated with clubroot incidence (r = 0.72). These data will be used to model clubroot development on canola based on temperature, rainfall and soil moisture.
Management of Stemphylium leaf spot (Stemphylium vesicarium) of asparagus (Asparagus officinalis) with fertility and disease forecasting. J. M. FOSTER AND M. R. MCDONALD. Department of Plant Agriculture, Crop Science Building, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
Stemphylium leaf spot, caused by Stemphylium vesicarium (Wallr.) Simmons, is a foliar disease of asparagus (Asparagus officinalis L.) that reduces the spear quality at harvest and prematurely defoliates the fern, which decreases the yield in subsequent crops. Currently, growers rely on protectant foliar fungicides applied to the fern every 10 to 14 days. Previous studies have established the forecasting model TOM-Cast as an effective tool to time foliar fungicides based on in-field weather data. The objectives of this research were to: (1) compare TOM-Cast calculated from in-field or site-specific weather data, and (2) assess fungicide programmes in an aggressive or standard fertility programme. In 2014, a trial arranged in a randomized complete block design was placed in a 10-year-old commercial ‘Millennium’ asparagus field to evaluate 14-day and TOM-Cast (in-field and site-specific) fungicide programmes that included chlorothalonil, metiram and/or azoxystrobin + difenoconazole. In the same field, a second trial was arranged in split-block design to compare fungicides applied on either a 14-day interval or according to TOM-Cast (in-field) in fern that was fertilized only pre-harvest or both pre- and post-harvest. By 2 October, TOM-Cast treatments from in-field and site-specific weather data had similar foliar yellowing (%), defoliation (%) and AUDPC values (P ≤ 0.05). In the fertilizer trial, the programme that included two fertilizer applications had a lower AUDPC value than the programme with a single fertilizer application by 2 October (P ≤ 0.05). Further research is warranted to validate the results and to establish fertilizer recommendations in new asparagus cultivars.
The effect of organic fungicides on apple scab (Venturia inaequalis) in McIntosh apples. A. HALDAR, A. ZWIEP, C. JACKSON, K. SCHNEIDER AND D. ERRAMPALLI. Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, 4902 Victoria Avenue North, Vineland Station, ON L0R 2E0, Canada
Apple scab disease is caused by the fungal pathogen Venturia inaequalis (Cooke) Wint. and can become a problem under favourable conditions in Ontario. This disease can be quite destructive to apple orchards leading to reduced yields and economic losses. Apple scab disease is often hard to manage due to the development of fungicide resistance by V. inaequalis. This study aims to examine the effect of organic fungicides against V. inaequalis to reduce development of apple scab in McIntosh apples in the orchard during the 2014 growing season. The apples were sprayed to run off with three organic fungicides, a water control and a chemical control (N-trichloromethylthio-4-cyclohexene-1,2-dicarboximide, Captan). The three organic fungicides used were 80% Sulphur (Kumulus) and 0.25% Reynoutria sachalinensis and 0.25% pre bloom and 0.75% post bloom R. sachalinensis (Regalia #1 and #2 respectively). Foliar rating scale was used to take weekly observations of the presence of apple scab on ‘McIntosh’ apple tree leaves. Disease ratings on fruits were taken at three times. Observations showed a gradual increase in apple scab disease progression over 3 months. Two-way ANOVA tests were also performed to determine statistical differences between and among all five treatments. The results indicated that Sulphur was the most effective treatment in reducing apple scab disease in ‘McIntosh’ apple leaves and fruits. Reynoutria sachalinensis organic fungicide treatment also significantly reduced apple scab disease in ‘McIntosh’ apple fruits.
Identification of multiple fungicide resistance in Botrytis cinerea from strawberries. C. JACKSON, A. ZWIEP, A. HALDAR AND D. ERRAMPALLI. Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, 4902 Victoria Avenue North, Vineland Station, ON L0R 2E0, Canada
Botrytis cinerea Pers.: Fr. is a fungus that causes grey mould and is damaging to soft fruits such as strawberry crops. This reduces the strawberry crop yield and available product for markets, resulting in economic losses. However, isolates of B. cinerea from strawberries have developed multiple fungicide resistance against some commonly used fungicides. This study aims to identify fungicide resistance in B. cinerea isolates collected from strawberries and determine the most effective reduced risk fungicide. Thirty isolates from B. cinerea collected from four locations were tested with seven fungicides at six concentrations to determine the EC50 value. The EC50 values were then used to classify isolates as sensitive or resistant (medium or high resistance) against each of the fungicides. The fungicides have various modes of action, and include cyprodinil and pyrimethanil which are aniliopyrimidines; fludioxonil, a phenylpyrrole; iprodione, a dicarboximide; and thiabenzadole, a benzimidazole. Additionally, combination fungicides, fludioxonil and cyprodinil, and boscalid (succinate dehydrogenase inhibitor) and pyraclostrobin (quinone-outside inhibitor) were tested. The results showed that B. cinerea isolates from strawberries had multiple fungicide resistance in all four locations. Fludioxonil or iprodione were the most effective reduced risk fungicides against multiple fungicide resistant B. cinerea isolates in all locations.
The effect of fungicide and nitrogen on agronomy, diseases, mycotoxins level and quality of ‘Princeton’ wheat. L. TAMBURIC-ILINCIC AND J. BRINKMAN. University of Guelph, Ridgetown Campus, 120 Main Street East, Ridgetown, ON N0P 2C0, Canada
The objective of the study was to investigate the effect of nitrogen, fungicides, and their potential interaction on leaf diseases, Fusarium head blight (FHB) symptoms, Fusarium damaged kernels (FDK) level, deoxynivalenol (DON) levels and agronomic characteristics in ‘Princeton’ wheat planted at Ridgetown, Ontario in 2012. The treatments included three spring N rates (75, 100 and 125 kg N ha−1) and three fungicide regimes consisting of an untreated control, QUILT + PROSARO with QUILT applied at flag leaf stage (ZGS 39) followed by PROSARO applied at 50% anthesis (ZGS 60), or PROLINE applied at ZGS 60. Disease severity for powdery mildew and septoria tritici blotch were recorded, while FHB symptoms were recorded as incidence and severity. DON concentration was determined by GC-MS method. FDK levels were measured using a SpecStar 2500-X Near Infrared Analyzer. There was no significant interaction between N rates and fungicide application for any trait. Both fungicides treatments resulted in increased yield at the 100 kg N ha−1 and decreased FHB index at all N levels, when compared with the respective control. Average FDK and DON level across all treatments was 7.5% and 1.2 ppm, respectively. QUILT + PROSARO significantly decreased powdery mildew levels under all nitrogen levels, while PROLINE only reduced the level at the 75 kg N ha−1 rate. Protein level in grain was significantly reduced by the QUILT + PROSARO treatment at the lowest N level (75 kg ha−1). The highest FDK (10.5%) and DON level (2 ppm) was obtained after application of 125 kg N ha−1 and without fungicides.
Controlling root-knot nematode (Meloidogyne hapla) on carrots and tomatoes with non-fumigant nematicides in Ontario. D. VAN DYK, K. JORDAN AND M. R. MCDONALD. Department of Plant Agriculture, Crop Science Building, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
Plant parasitic nematodes such as the root-knot nematode (Meloidogyne hapla Chitwood) are becoming a growing concern in Ontario on carrots (Daucus carota L., subsp. sativus (Hoffm) Arcang) and tomatoes (Solanum lycopersicum L.). Management options are limited and further restrictions on registered fumigant use have been implemented as of September 2014, so finding new non-fumigant nematicides is a priority. Growth room trials were conducted on carrot in muck soil (organic matter 69.4%) and tomato in mineral soil (organic matter 1.8%). The soil was inoculated with Meloidogyne hapla at a rate of 1097 eggs 100 cm−3. The treatments were metam sodium (42.5%, 210 L a.i. ha−1), dazomet (99.0%, 277 kg a.i. ha−1), Dazitol (capsaicin 0.42%, oleoresin of capsicum 3.7%, 59 L a.i. ha−1), MustGrow (oriental mustard seed meal 100%, 1680 kg ha−1), Movento (spirotetramat 24%, 685 g a.i. ha−1), Agri-Mek (abamectin 2%, 2 L a.i. ha−1), and Nimitz (fluensulfone 15%, 4 kg a.i. ha−1). Inoculated and non-inoculated checks were included. Carrots cultivar ‘Cellobunch’ and tomatoes cultivar ‘Rutgers’ were seeded and transplanted into conetainers. Carrots treated with dazomet and the un-inoculated check had more per cent healthy than the inoculated check. Tomatoes treated with metam sodium, dazomet, Nimitz and the un-inoculated check significantly reduced per cent root infested compared with all other treatments. Abamectin also significantly reduced per cent root infested compared with the inoculated check. Tomatoes treated with metam sodium and dazomet had significantly higher dry top weight compared with all other treatments while Nimitz and abamectin had significantly higher dry top weight than the inoculated check.