A field trial was conducted at Fargo, North Dakota, in 2005 and 2006 to evaluate different fungicide application methods on soybean (Glycine max). Kromekote ® paper cards were placed in the upper and lower canopy of soybean plants, and tebuconazole fungicide mixed with a blue dye was sprayed with different application methods at the R5 developmental stage. The applications were made with a conventional sprayer with Turbo TeeJet ® 110015 flatfan nozzles at 276 kPa liquid pressure, a conventional sprayer with XR TeeJet ® 80015 flat-fan nozzles at 276 kPa liquid pressure, an AirJet ® bifluid nozzle spray system with liquid pressure at 276 kPa and air pressure at both 76 and 48 kPa, or an air-assisted spray system with liquid pressure at both 221 and 83 kPa. An untreated control was also included to evaluate the effect of tebuconazole on soybean yield. Dye-sensitive Kromekote paper cards were analyzed to determine the percent coverage and the volume median diameter (VMD) of the droplets. Significant (P ≤ 0.05) interactions between year and application method were detected, most likely resulting from differences in plant height and development between the years. Droplet coverage in the upper canopy did not differ in either year among the application methods. Most application methods provided similar droplet coverage in the lower canopy in 2005, but the conventional sprayer with XR TeeJet 80015 flat-fan nozzles provided the greatest coverage in the lower canopy in 2006. Correlation analysis indicated that droplet coverage in the lower canopy increased with increased VMD of the droplets in 2005 (R = 0.91), and that yield increased with increased fungicide coverage in 2006 (R = 0.85). Visible symptoms of foliar fungal diseases were not present in either year, and tebuconazole had no effect on soybean yield, compared with the untreated control in either year. Bradley et al.: soybean / fungicide application / comparison of methods 202 Résumé : En 2005 et 2006, un essai au champ fut mené à Fargo, Dakota du Nord, pour évaluer différentes méthodes d'application de fongicides sur le soja (Glycine max). Des cartes de papier Kromekotez furent placées aux niveaux supérieur et inférieur du couvert végétal du soja, et du fongicide tébuconazole, mélangé à un colorant bleu, fut pulvérisé selon différentes méthodes d'application au stade de développement R5. Les applications ont été effectuées avec un pulvérisateur traditionnel équipé de buses à jet plat Turbo TeeJetz 110015 à une pression du liquide de 276 kPa, un pulvérisateur traditionnel équipé de buses à jet plat XR TeeJetz 80015 à une pression du liquide de 276 kPa, un système de pulvérisation équipé de buses AirJetz à émulsions inverties multiphases à une pression du liquide de 276 kPa et une pression d'air de 76 et 48 kPa, ou un système de pulvérisation à air assisté à une pression du liquide de 221 et 83 kPa. Un témoin non traité fut aussi inclus pour évaluer l'effet du tébuconazole sur le rendement du soja. Les cartes de papier Kromekote sensible au colorant furent analysée...

Borage (Borago officinalis) is an oilseed crop that is being evaluated as an alternative crop in North Dakota. During September 2004, borage plants in a field in Cass County, North Dakota were dying from a watery soft rot. The main stems and lateral branches were affected, and affected plants were usually completely lodged and prostrate. Dead plants had bleached and shredded stems with black sclerotia (9.1 ± 3.0 × 2.6 ± 0.5 mm) inside the pith and on the epidermis. At the time of observation, borage plants were flowering and forming pods and seed. Approximately 60% of the plants were visually affected by the watery soft rot. Sclerotia were collected from diseased plants, soaked in a 0.5% NaOCL solution for 30 s, air dried, and placed in petri dishes containing potato dextrose agar (PDA). A fungus grew from the plated sclerotia that subsequently produced white mycelium and black sclerotia (4.8 ± 1.2 × 2.5 ± 1.0 mm), which is characteristic of Sclerotinia sclerotiorum (Lib.) de Bary (3). To confirm pathogenicity, borage plants were inoculated in the greenhouse with a S. sclerotiorum isolate from field-infected borage. Thirteen borage plants were grown from seed in the greenhouse under natural sunlight at a temperature range of 24 ± 3°C. When plants were at the four-leaf stage (approximately 16 cm high), the second leaf was excised from each plant with the petiole remaining on the plant. The leafless petioles were inoculated using a method previously described (2). Petioles of 10 plants were inoculated with PDA containing mycelium of the S. sclerotiorum borage isolate, while petioles of five plants were inoculated with PDA to serve as a control. Three days after inoculation, plants inoculated with the S. sclerotiorum borage isolate were beginning to wilt and 5 days after inoculation, these plants were completely wilted and prostrate, similar to observations made on field-infected plants. Sclerotia collected from the diseased, inoculated plants were placed on PDA, and S. sclerotiorum was successfully recovered. Control plants inoculated with PDA did not show any disease symptoms. Other plant genera in the Boraginaceae are known hosts of S. sclerotiorum (1); however, to our knowledge, this is the first report of borage as a host. References: (1) G. J. Boland and R. Hall, Can. J. Plant Pathol. 16:93, 1994. (2) L. E. del Río et al. (Abstr.) Phytopathology 90(suppl.):S176, 2000. (3) D. L. Tourneau, Phytopathology 69:887, 1979.