Foliar Fungicide Study Block 5S Beaumont, TX 2009

Transcription

1 North Foliar Fungicide Study Block 5S Beaumont, TX 2009 Young-Ki Jo, X. Mao, M.O. Way, Don Groth and Piper Roberts PLOT PLAN I II III IV Plot size: 7 rows, 7 inch row spacing, 18 ft long Variety: Cocodrie (seed provided by LSU Foundation Seed) Note: smaller numbers in italics are plot numbers 46

2 TREATMENT DESCRIPTION, RATE AND TIMING Main Crop Ratoon Crop Trt. no. Treatment (fl oz prod/a) Treatment (fl oz prod/a) 1 Evito 480 SC + COC 3 Quadris 12 2 Evito 480 SC + COC 4 Quilt 20 3 Evito 480 SC + COC 5.7 Stratego 19 4 A15909 (AZO + PPZ) 17.5 Stratego 19 5 A15909 (AZO + PPZ) + Quadris SC + Tilt EC Evito + COC A13705 (Quilt) + Quadris SC Convoy Quilt SE 20 Stratego 19 8 Quadris SC 12 Quilt 20 9 Stratego EC 19 Quadris Stratego + Gem 500 SC Evito + COC Stratego + Gem 500 SC Convoy Stratego + Quadris F Quilt Convoy 40 SC 11.7 Artisan Convoy 40 SC 16.8 Artisan Convoy 40 SC 23.4 Quadris Artisan SE 15 Convoy Artisan SE 22.5 Convoy Untreated --- Untreated --- All treatments applied at 4 panicle 47

3 Agronomic and Cultural Information Experimental design: Randomized complete block with 18 treatments and 4 replications Planting: Drill-planted 80 lb/a into League soil (ph 5.5, sand 3.2%, silt 32.4%, clay 64.4%, and organic matter %) on Apr 6 Plot size = 7 rows, 7 inch row spacing, 18 ft long (no metal barriers) Emergence on Apr 15 Irrigation: Flushed blocks (temporary flood for 48 hours, then drain) on Apr 6 Note: Plots were flushed as needed from emergence to permanent flood Permanent flood (PF) on May 7 Ratoon flood on Aug 6 Fertilization: All fertilizer (urea) was distributed by hand lb N/A (1/3 of 170) on Apr 6 at planting 56.7 lb N/A (1/3 of 170) on May 7 at PF 56/7 lb N/A (1/3 of 170) on May 27 at 2 weeks after PF 40 lb N/A on Jun 22 Total main nitrogen = 210 lb N/A 100 lb N/A for ratoon on Aug 6 Total ratoon nitrogen = 100 lb N/A Herbicide: Stam 2.0 lb, 0.75 lb, Facet 0.25 lb and 2.0 lb (AI)/A and 1.0 pt/acre with a 2-person hand-held spray boom ( nozzles, 50 mesh screens, 16 gpa final spray volume) on May 6 for early season weed control Treatments: Inoculated with sheath blight (SB) inoculum (Rhizoctonia solani) on May 28. The inoculum was prepared using 5 parts rice hulls and 1 part whole rice substrate colonized with R.solani. Fungicide treatments for main crop applied with a 3-nozzle CO 2 pressurized spray boom ( nozzles and 50 mesh screens) on Jun 19 (12 days after panicle differentiation) by Dr. Jo Fungicide treatments for ratoon crop applied on Aug 27 by Dr. Jo Sampling: Stand counts on plots 3, 27, 42 and 66 as well as bird damaged plots 18, 36, 54, and 72 (3-3 ft counts on rows 2, 4 and 6) on May 2 Water was unintentionally added to block after inoculation which probably reduced SB severity; 1 panicle on Jun 12 Disease ratings by Dr. Jo on Jul 9, Jul 31 and Oct 5 Harvest: Harvested main crop plots on Aug 3 Size harvested plot = 7 rows, 7 inch row spacing, 18 ft long Harvested ratoon crop plots on Oct 21 Size harvested plot = 7 rows, 7 inch row spacing, 18 ft long 48

4 Data analysis: Yields converted to 12% moisture; all data analyzed by ANOVA and means separated by Fisher s Protected LSD (alpha 0.05). Discussion Sheath blight severity was not as high as desired, but mean severity in the non-treated control plots reached 7 in which lesions affected the lower ¾ of the sheaths and extended to leaf blades of the lower ⅔ of the plants. Most treatments significantly reduced disease severity compared to the non-treated control. A tank-mixture of azoxystrobin and propiconazole provided the best control; however, yields were not significantly different among treatments. The fungicide treatments on the main crop significantly increased the number of healthy tillers of the ratoon crop. Mixture of trizole and strobilurin fungicides applied for the main crop provided more than 90% tiller stands of the ratoon crop, compared with the non-treated control plot having only 76.3% viable tillers (Table 1). The fungicide treatments on the ratoon crop applied at 24 days after main crop harvest did not affect the disease severity of brown leaf spot and narrow brown leaf spot, and did not increase the yield of the ratoon crop. The main crop disease management seems to have a direct impact on the ratoon crop management. Table 1. Mean disease ratings for main crop. Beaumont, TX Treatment (fl oz/a) Sheath blight disease rating a % stand of ratoon crop Evito 480 SC + COC ed 83.8 c-g Evito 480 SC + COC a-d 81.3 e-g Evito 480 SC + COC b-d 87.5 a-f A15909 (AZO + PPZ) ef 91.3 a-d A15909 (AZO + PPZ) + Quadris SC + Tilt EC ef 96.3 a A13705 (Quilt) + Quadris SC f 90.0 a-e Quilt SE d-f 93.8 ab Quadris SC ef 93.8 ab Stratego EC b-d 91.3 a-d Stratego + Gem 500 SC de 92.5 a-c Stratego + Gem 500 SC d-f 93.8 ab Stratego + Quadris F d-f 93.8 ab Convoy 40 SC b-d 91.3 a-d Convoy 40 SC cd 78.8 fg Convoy 40 SC de 83.8 c-g Artisan SE ab 82.5 d-g Artisan SE b-d 86.3 b-f Untreated a 76.3 g a Sheath blight rating 0 (no disease) to 9 (plant collapsed) Means in a column followed by the same letter are not significantly different (P = 0.05). 49

5 Table 2. Mean disease ratings for ratoon crop. Beaumont, TX % stand of Brown leaf spot Narrow brown leaf spot Treatment (fl oz/a) ratoon crop Incidence Severity Incidence Severity Quadris c-g Quilt e-g Stratego a-f Stratego a-d Evito + COC a Convoy a-e Stratego ab Quilt ab Quadris a-d Evito + COC a-c Convoy ab Quilt ab Artisan a-d Artisan fg Quadris c-g Convoy d-g Convoy b-f Untreated g NS NS NS NS Means in a column followed by the same or no letter are not significantly (NS) different (P = 0.05, ANOVA and LSD). 50

6 Table 3. Mean yield data for main and ratoon crop. Beaumont, TX Main Crop Ratoon Crop Yield (lb/a) Treatment (fl oz prod/a) Treatment (fl oz prod/a) M R T Evito + COC 3 Quadris Evito + COC 4 Quilt Evito + COC 5.7 Stratego A15909 (AZO + PPZ) 17.5 Stratego A15909 (AZO + PPZ) + Quadris 2.08 SC + Tilt 3.6 EC Evito + COC A13705 (Quilt) + Quadris 2.08 SC Convoy Quilt 20 Stratego Quadris 12 Quilt Stratego 19 Quadris Stratego + Gem 500 SC Evito + COC Stratego + Gem 500 SC Convoy Stratego + Quadris 2F Quilt Convoy 11.7 Artisan Convoy 16.8 Artisan Convoy 23.4 Quadris Artisan 15 Convoy Artisan 22.5 Convoy Untreated --- Untreated NS NS NS Means in a column are not significantly (NS) different (P = 0.05, ANOVA) 51