Uniform Fungicide Trials for Suppressing FHB

Uniform fungicide trials are conducted in a number of wheat-producing states each year, including Minnesota, to provide a non-biased evaluation of experimental FHB chemical control products for hard red spring wheat and barley.  Cooperatively, the multi-state uniform fungicide trials (funded through the U.S. Wheat and Barley Scab Initiative) indicate which fungicide compounds are most effective in reducing disease severity across diverse environments.

Wheat and barley experiments were planted in Crookston on April 28, 2003.  ‘Oxen’ hard red spring wheat and ‘Robust’ spring barley were seeded at 1.25 mil. seed/acre and 1.375 mil. live seed/acre, respectively. Plots were inoculated with 250 g of Fusarium graminearum infested corn grain five weeks after planting.  Night-cycle mist irrigation was initiated the day after inoculation and continued until plants began to senesce.

Treatments (labeled products as well as non-labeled experimentals) were applied to wheat nine weeks after planting [Feekes 10.51 growth stage (early flowering)] and to barley eight weeks after planting [Feekes 10.4 (early heading)].  Disease severity responses (Figure 2) were noted 22 and 25 days after treatment application from wheat and barley, respectively. Tests were harvested 15 weeks after planting.

As expected, the nontreated control had the most severe disease response for all parameters tested (Table 1).  JAU6476 480SC 3.6 fl. oz. + Folicur 3.6F 4 fl. oz. significantly reduced disease , and increased yield and quality factors in all reported categories, compared with the control. While not statistically significant from other fungicide treatments, V-10116 1.67SC 6 fl. oz. had most reduced VSK (74%) and DON levels (55%) compared with the nontreated control.

Severe weather conditions during Feekes growth stage 10 (booting) caused barley plants in all replicates to lodge. Plant lodging occurred approximately five days before treatments were applied. As a result, barley data must be weighed against the percent plot lodged rating (Table 2) before assessing treatment effectiveness. Nontreated control plots had the least plants lodged (58.8%) which resulted in reduced disease severity compared with Folicur 3.6F 4 fl. oz. treated plots (81% lodged).  V-10116 1.67SC 8 fl. oz. reduced FHB head severity by 17%, FHB field severity by 31%, and DON by 38% compared with the control, in spite of its 80% lodging score.

Table 1: FHB and Foliage Disease Responses¹ from ‘Oxen’ Spring Wheat, Crookston, Minnesota

Fusarium Head Blight       HS3 I FS VSK DON LDS 4 Yield TW Treatment 2 % % % % ppm % bu/a lb/bu Nontreated control 5.9 98.5 35.7 17.5 15.0 3.4 52.0 53.8 Folicar 3.6F 4fl oz 4.3 91.5 18.9 8.0 11.2 2.1 65.9 55.4 JAU6476 480SC 5.7 fl/oz 3.6 73.0 13.9 10.0 12.9 2.4 64.4 55.5 JAN6476 480SC 3.6 fl/oz + Folicure 3.6F 4 fl/oz 3.1 73.5 8.7 5.0 9.1 1.7 73.9 57.3 V-10116 1.67SC 6 fl/oz 3.5 84.0 11.8 4.5 6.7 2.2 73.1 56.9 V-10116 1.67SC 8 fl/oz 3.8 83.0 14.0 5.0 7.4 1.8 74.0 56.5 LSD 0.05 0.3 16.5 10.7 4.8 3.2 0.3 8.4 1.2 1Rating abbreviations are HS: head severity; I: incidence; FS: field severity; VSK: visually scabby kernels; LDS: leaf disease severity. 2 Each fungicide treatment included 0.125% Induce. 2 Square root transformation. 3 Log transformation. Foliar diseases consisted of Stagonospora blotch (Stagonospora nodorum) and Tan spot (Pyrenophora tritici-repentis)

TABLE 2: FHB and Foliage Disease Responses ¹ from ‘Robust’ Barley in Crookston, Minnesota

Fusarium Head Blight       % Plots HS 3 I FS DON LDS 4 Plump Yield TW Treatment Lodged 2 % % % ppm % Kernels bu/a lb/bu Nontreated control 58.8 4.8 100 24.7 36.2 2.7 73.2 88.4 41.6 JAU6476 480SC 5.7 fl oz 86.3 4.6 100 24.1 25.5 2.7 76.6 96.1 42.6 JAU6476 480SC 5.0 fl oz 77.5 4.1 100 19.1 28.2 2.7 78.1 104.1 42.5 JAU6476 480SC 3.6 fl oz + Folicur 3.6F 4 fl oz 86.3 4.3 100 21.7 23.1 2.5 76.2 95.4 42.1 V-10116 1.67SC 6 fl oz 63.8 4.6 100 23.7 28.0 2.7 76.8 93.5 41.8 V-10116 1.67SC 8 fl oz 80.0 4.0 100 17.1 22.5 2.6 75.9 99.8 42.3 LSD 0.005 0.4 NS NS 8.0 0.4 NS NS NS   1 Each fungicide treatment included 0.125% Induce. Treatment abbreviations are as follows: HS-head severity; I-incidence; FS-field severity; VSK-visually scabby kernels; LDS-leaf disease severity. 2 Severe weather caused plants to lodge between 21-24 June, 2003; approximately five days before treatments were applied. Plot lodging assessments were taken six weeks after plants went down.  3 Square root transformation. 4 Log transformation. Foliar diseases consisted of Septoria speckled leaf blotch (Septoria passerinii and Stagonospora avenae f. sp. triticea), net blotch (Pyrenophora teres) and spot blotch (Cochliobolus sativus).

– Dr Char Hollingsworth, U of M extension plant pathologist, Crookston