Improved Fungicide Efficacy on Canola through Application Technology

 

Scott Halley* and John Lukach

Langdon Research Extension Center, North Dakota State University, Langdon, ND 58249,

*Corresponding Author: PH: (701) 256-2582, E-mail: shalley@ndsuext.nodak.edu

 

A research trial was conducted in 2002 and 2003 to evaluate fungicide spray application technology with Ronilan (vinclozolin) fungicide for control of white mold, Sclerotinia sclerotiorum (Lib) de Bary, in canola. A split split plot design (2 x 3 x 3) compared early and late planting date and three sprayer systems; a conventional type equipped with hydraulic nozzles oriented vertical; a modified Spray-air� sprayer with an air-assisted spray distribution system oriented vertically down; and a Spray-air oriented forward and backward. The conventional spray system uses CO₂ to deliver the solution through a XR8002 flat fan nozzle spaced 20 inches on center at 40 psi. The Spray-air system also used CO₂ to deliver the solution through an orifice. An air stream, created by a hydraulically driven centrifugal fan, picks up the solution, creates a drop using air shear technology, and delivers the fungicide to the target through orifices spaced 10 in apart. The system was modified from original equipment specifications to spray at an angle 30� downward from horizontal and optionally forward and backward. Spray volumes of 5.2, 10.4, and 19.2 GPA were the third set of factors and were adjusted by tractor travel speed.

 

Materials and Methods

 

The sites, previous crop barley both years, were planted with a double disk drill, disks spaced 6 inches, to plots 7 rows wide 16 ft long. An additional border area 6.5 ft wide was planted between plots to accommodate the tractor travel, to reduce drift to adjacent plots, and to create a field type environment conducive to white mold disease development. Cultivars �InVigor 2733� and �Hyola 357 Magnum� were planted on 14 May and 30 May 2002 and 13 May and 2 Jun 2003, respectively. Recommended production practices for Northeast North Dakota, NDSU Extension, were followed. Two inoculation techniques were used to improve chance of white mold infections. In 2002 sclerotia were hand broadcast and shallowly incorporated in spring after conditioning by three in vitro freeze/thaw cycles of 14 days duration each. This conditioning technique was modified in 2003. Sclerotia were blended with soil to achieve a 50% soil/sclerotia mix by volume and 30% water by weight was added before a single in vitro freeze cycle of 6 weeks. In 2003 the conditioned sclerotia were hand broadcast and shallowly soil covered both in fall and spring before seeding to increase potential for white mold infection. The 2003 technique was more effective in producing apothecia throughout the growing season than the 2002 technique.

 

Ronilan fungicide was applied at 12 oz/acre. Fungicide was applied on 2 and 16 Jul and 1 and 19 July in 2002 and 2003, respectively, at 30% bloom stage of growth.� In 2003 Day-Glo orange fluorescent dye was added to the spray solution at 1.75% v/v to measure fungicide coverage on the flowers. Compatibility of the fungicide and the dye were determined by Surinam Panigrahi, NDSU Ag Engineering and Biosystems Department the previous winter. A second technique was implemented inn both growing seasons to increase chance of white mold infection. On 1 and 16 Jul 2002 and 6 and 24 Jul 2003, ascospores at 5000 spores/ml were sprayed by backpack sprayer at 9.2 GPA and 40 psi at 30 to 50% bloom growth stage. A later than expected delivery date of the digital camera coupled with a software problem did not permit collection of spray coverage data in 2002. Flowers were clipped, bagged, and transferred to cold storage. As soon as fungicide applications concluded, an Optronics CCD digital video camera was used to photograph the flowers under incandescent light, to determine the area of the target, and under ultraviolet light to determine the area covered by the spray solution. The target, fresh canola flowers, disintegrated almost immediately after removal from the plant. No usable data was collected on spray coverage from the early plant timing. Following fungicide application, late plant 2003, leaves in the lower canopy were collected and spray coverage was determined by procedure described previously. Infection due to white mold disease was determined by counting two rows 16 ft long and individually giving each plant 0, 0.5, 1 where 0=no visible disease, 0.5=infection of one or more branches, 1=infection of main stem. Plots were swathed and harvested after dry down.� The seed sample was cleaned and processed to determine yield and test weight. Additionally, oil and thousand seed weight (TSW) were measured in 2002. �Data were analyzed with the general linear model (GLM) in SAS. Least significant differences (LSD) were used to compare means at the 5% probability level.

 

Results and Discussion

 

Increases in yield and test weight by plant date (Table 3) and a reduction in sclerotinia by plant date, 2003 (Table 7), were measured. Additionally, a difference in thousand seed weight by plant date, sprayer system, and GPA was also detected (Table 6). No differences in leaf coverage were detected.

 

The study brought to attention several of the difficulties in doing sclerotinia research. Successes in achieving desired levels of white mold infections in other trials were achieved with supplemental water applications to the soil and crop canopy. Water applied to the soil before flowering enhanced carpogenetic germination of the sclerotia. Supplemental water at flowering promoted an environment conducive to disease infection. Watering systems currently used in other studies would be difficult to use with tractor mounted application technology studies. A small wheel irrigation unit will need to be acquired for future fungicide application technology trials utilizing tractor spray systems. The canola flower deteriorated rapidly after removal from the plant. Further deterioration was accelerated by the heat generated by the lights of the camera system. A portable video imaging unit to collect and record the data while the flower is intact on the plant in the field is needed and has been proposed by Dr. Suranjan Panigrahi of NDSU Ag Engineering and Biosystems Department. I will look forward to working with him on projects when the technology is available for field use. Large areas of the leaves in the lower canopy received little or no fungicide from the spray application. The probable cause was interference from other plant structures, leaves and stems. It is probable that when later emerging flowers senesce and fall, infections can and will occur.� Research studies should be undertaken to address these issues.

 

 

 

 

 

Table 1. Yield and test weight by year, plant date, sprayer system, and GPA.

Plant Date	Sprayer System	GPA1	Yield	Test Weight
			bu/A	lb/bu
2002
Early
	Conventional Down	5.2	1235	50.1
		10.4	1072	49.2
		19.2	1273	49.8
	Spray-Air Down	5.2	1415	49.8
		10.4	1418	49.8
		19.2	1118	50.3
	Spray-Air F+B	5.2	1030	50.0
		10.4	1305	49.8
		19.2	1312	50.0
Late	Conventional Down	5.2	1243	51.1
		10.4	1265	51.0
		19.2	1113	50.6
	Spray-Air Down	5.2	1022	51.0
		10.4	1250	51.1
		19.2	1240	50.4
	Spray-Air F+B	5.2	1243	51.0
		10.4	1153	51.0
		19.2	1148	50.6
2003
Early	Conventional Down	5.2	1955	51.9
		10.4	1927	51.8
		19.2	2208	51.8
	Spray-Air Down	5.2	1896	51.5
		10.4	2192	52.1
		19.2	1939	51.8
	Spray-Air F+B	5.2	2139	51.4
		10.4	2050	51.9
		19.2	2060	52.1
Late	Conventional Down	5.2	1633	52.3
		10.4	1574	52.3
		19.2	1633	52.5
	Spray-Air Down	5.2	1564	52.4
		10.4	1561	52.3
		19.2	1567	52.6
	Spray-Air F+B	5.2	1615	52.6
		10.4	1684	52.3
		19.2	1522	52.5

¹Gallons per acre

 

 

 

Table 2. Yield and test weight by plant date and sprayer system by year, plant date and GPA by year, and GPA by year.

Plant Date	Sprayer System	GPA1	Yield	Test Weight
			bu/A	lb/bu
Plant date by sprayer system averaged across GPA
2002
Early	Conventional Down		1193	49.7
	SprayAir Down		1317	49.9
	SprayAir F + B		1216	49.9
Late	Conventional Down		1207	50.9
	SprayAir Down		1171	50.8
	SprayAir F + B		1181	50.9
2003
Early	Conventional Down		2030	51.8
	SprayAir Down		2009	51.8
	SprayAir F + B		2083	51.8
Late	Conventional Down		1613	52.3
	SprayAir Down		1564	52.4
	SprayAir F + B		1607	52.5
Plant date by GPA averaged across sprayer systems
2002
Early		5.2	1227	50.0
		10.4	1265	49.6
		19.2	1234	50.0
Late		5.2	1169	51.0
		10.4	1223	51.0
		19.2	1167	50.5
2003
Early		5.2	1997	51.6
		10.4	2056	51.9
		19.2	2069	51.9
Late		5.2	1604	52.4
		10.4	1606	52.3
		19.2	1594	52.5
LSD
GPA averaged across plant dates and sprayer systems
2002		5.2	1198	50.5
		10.4	1244	50.3
		19.2	1200	50.3
2003		5.2	1800	52.0
		10.4	1831	52.1
		19.2	1822	52.2

¹Gallons per acre

 

 

Table 3.� Yield and test weight by year, sprayer system, and GPA, plant date by year, and sprayer system by year.

Plant Date	Sprayer System	GPA1	Yield	Test Weight
			bu/A	lb/bu
Sprayer system by GPA averaged across plant dates
2002	Conventional Down	5.2	1239	50.6
		10.4	1168	50.1
		19.2	1193	50.2
	Spray-Air Down	5.2	1219	50.4
		10.4	1334	50.4
		19.2	1179	50.3
	Spray-Air F+B	5.2	1136	50.5
		10.4	1229	50.4
		19.2	1230	50.3
2003	Conventional Down	5.2	1794	50.1
		10.4	1750	52.0
		19.2	1920	52.1
	Spray-Air Down	5.2	1730	51.9
		10.4	1877	52.2
		19.2	1753	52.2
	Spray-Air F+B	5.2	1877	52.0
		10.4	1867	52.1
		19.2	1791	52.3
Plant date averaged across sprayer systems and GPA
2002
Early			1242	49.8
Late			1186	50.9
2003
Early			2041	51.8
Late			1595	52.4
LSD			207	0.5
Sprayer system averaged across plant dates and GPA
2002	Conventional Down		1200	50.3
	SprayAir Down		1244	50.4
	SprayAir F + B		1198	50.4
2003	Conventional Down		1822	52.1
	SprayAir Down		1786	52.1
	SprayAir F + B		1845	52.1

¹Gallons per acre

 

 

 

 

 

 

 

Table 4. Yield and test weight by plant date, sprayer system, GPA, plant date by sprayer system, sprayer system by GPA, and plant date by GPA.

Plant Date

Sprayer System

GPA1