2007 Extension Research Report
Disease Management
EVALUATION OF FUNGICIDES AND SPRAY PROGRAMS FOR
CONTROL OF POWDER MILDEW IN BUTTERNUT SQUASH IN
GEORGIA 2006
D. B. Langston, Jr., University of Georgia Coop. Ext. Ser., Dept. Plant Pathology, Tifton, GA 31793
to deliver 40 gal/A at 75-80 psi through TX-18
hollow cone nozzles. Rainfall for Sep and Oct
combined was 3.2 in. which is 2.8 in. below the
91 yr average.
Materials and Methods
Squash seed were planted on 5 Sep in black
plastic mulch covered beds at the Horticulture
Farm, a unit of the Coastal Plain Experiment
Station in Tifton, GA. Mulched beds had a 36in. top, were laid on 6-ft centers, and were
painted with white paint prior to planting. Seed
were planted in one row per bed and were
spaced 2 ft apart within the row, resulting in 8
plants per plot. Plots were 15 ft long, were
separated on each end by 5 ft of bare plastic, and
were arranged in a randomized complete block
design with five replications. Fertility, insects
and weeds were managed according to standard
University of Georgia Extension Service
recommendations. Fungicide treatments were
applied with Lee Spider Spray Trac® calibrated
Results and Discussions
Powdery mildew was first observed on 2
Oct and increased to high levels by 27 Oct. All
treatments significantly suppressed powdery
mildew compared to non-treated plots by the 27
Oct rating except Serenade Max. Treatments
containing Quintec or Procure generally offered
superior performance compared to treatments
not containing these fungicides. Since disease
began after some fruit were harvested, yield was
not recorded and was likely unaffected.
Powdery mildewy
Treatments, rates/A, and (spray times)z
27 Oct
Quintec 250SC, 6.0 fl oz (1,3,6,8) .................................................................................................. 1.0 ex
Procure 480SC, 8.0 fl oz (1,3,6,8) .................................................................................................. 1.2 e
Quintec 250SC, 6.0 fl oz (1,6)
Procure 480SC, 8.0 fl oz (3,8) ........................................................................................................ 1.2 e
Procure 480SC, 8.0 fl oz (1,6)
Pristine 38WG, 14.5 oz (3,8) .......................................................................................................... 1.4 e
Procure 480SC, 6.0 fl oz (1,3,6,8) .................................................................................................. 1.4 e
Procure 480SC, 8.0 fl oz (1,6)
Quintec 250SC, 6.0 fl oz (3,8) ........................................................................................................ 2.0 de
Pristine 38WG, 14.5 oz (1,6)
Procure 480SC, 8.0 fl oz (3,8) ........................................................................................................ 2.0 de
V-10118 0.41EC, 6.2 fl oz (1,3,6,8) ............................................................................................... 3.4 d
Pristine 38WG, 14.5 oz (1,3,6,8) .................................................................................................... 3.4 d
V-10118 0.41EC, 9.3 fl oz (1,3,6,8) ............................................................................................... 5.2 c
Sonata AS, 2.0 qt + Biotune @ 1 pt/100 gal (1,2,5,6,8) ................................................................. 7.0 b
Serenade Max, 2.0 lb + Biotune @ 1 pt/100 gal (1,2,5,6,8) ........................................................... 7.4 ab
Non-treated ..................................................................................................................................... 9.0 a
z
Spray dates were: 1=25 Sep; 2=2 Oct; 3=4 Oct; 5=9 Oct; 6=13 Oct; 7=16 Oct; 8=18 Oct.
Powdery mildew was rated on a 1-10 scale where 1=1-10% leaf area affected by powdery mildew and
10=100% leaf area affected by powdery mildew on both upper and lower leaf surfaces.
x
Means followed by the same letter(s) are not significantly different according to Fisher’s protected LSD
test at P≤0.05.
y
76