Oakes
SUNFLOWER/SCLEROTINIA HEAD ROT STUDY
D. Lee, W. Albus, L. Besemann and H. Eslinger
Sunflower
head rot studies were initiated at the Carrington Extension Research Center in
2000. The National Sunflower
Association provided the funding in 2000 for the development of a misting
system that provides the environment for uniform disease infection when heads
are artificially inoculated. The following year the USDA Sclerotinia Initiative
was funded by Congress. This Project
has grown from the one site to multi locations in ND, MN and MB, Canada. The Oakes Irrigation Research Site was a
study site in 2007. Only sunflower
hybrids that had shown previous disease resistance at other sites and locations
were tested. These hybrids were
compared to tester hybrids with known resistance and tester hybrids with known
susceptibility.
MATERIALS AND METHODS
|
Soil: |
Hecla sandy loam and Maddock sandy loam;
pH=7.7; 1.9% organic matter; soil-P and soil-K was very high and soil-S was
very low. |
|
Previous crop: |
2006 – asparagus, tomato and pepper; 2005 –
asparagus and raspberry; 2004 - asparagus and raspberry; |
|
Seedbed Preparation: |
Fall coulter chisel. Multiweed (field cultivate) twice May 22
to smooth the seedbed and twice on May 29 to incorporate herbicide. |
|
Planting: |
Planted on June 6 in 30 inch rows with
about four inches between plants and were later thinned to 6 to 8 inches
between plants. |
|
Plots: |
Plots were 17 long by 2.5 ft wide. There were four reps. |
|
Fertilizer: |
No fertilizer was applied. |
|
Irrigation: |
Overhead sprinkler irrigation as needed. |
|
Pest control: |
Trust (1.5 pt/acre) on May 29 and handweeding
controlled weeds. |
|
Treatments |
Inoculate sunflower heads that are at the
correction stage on August 9, August
10, August 15 and August 20 and ran the misting system per the protocol
making adjustments as necessary. Ratings were taken three times beginning
two weeks after the final inoculation and at two week intervals from
September 3 to October1. |
Disease
ratings were taken September 3, September 17th and October 11th. The last two rating dates were used to
determine track potential increase in infection incidence and severity of
infection. The disease pressure was
very high in 2007. However, many
hybrids had greater resistance to sclerotinia head rot than the known resistant
check hybrid.
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Table 1. Sclerotinia
head rot, ratings on sunflower hybrids in an inoculated field at the Oakes Irrigation Research Site in 2007.
|
|
|
Sep-17 rating |
Oct-1 rating |
||
|
Company |
Hybrid |
Incidence |
Severity1 |
Incidence |
Severity |
|
|
|
% |
0-5 |
% |
0-5 |
|
Proseed |
E-3 |
55.0 |
2.5 |
100.0 |
3.7 |
|
Proseed |
E-4 |
56.7 |
3.6 |
100.0 |
3.9 |
|
Proseed |
E-85 |
56.7 |
2.8 |
96.7 |
3.4 |
|
Mycogen |
E86524 |
19.4 |
3.1 |
76.8 |
2.2 |
|
Mycogen |
E87355 |
55.0 |
3.1 |
96.7 |
3.1 |
|
Croplan |
343 DMR |
53.4 |
2.4 |
100.0 |
3.4 |
|
Croplan |
6N9 |
88.1 |
3.1 |
98.1 |
3.8 |
|
Croplan |
378 DMR, NS |
51.7 |
2.9 |
91.7 |
3.0 |
|
Seeds 2000 |
X4715 |
51.3 |
3.1 |
100.0 |
3.2 |
|
Seeds 2000 |
X5431 |
42.9 |
3.9 |
71.6 |
3.0 |
|
Triumph |
6443 |
56.7 |
3.9 |
95.0 |
3.4 |
|
Triumph |
6442 |
71.7 |
2.8 |
95.0 |
3.3 |
|
Pannar |
7813 NS |
65.0 |
2.9 |
95.0 |
3.6 |
|
Advanta |
F30294 |
48.3 |
2.5 |
81.7 |
3.0 |
|
Advanta |
F41271 |
81.1 |
2.6 |
100.0 |
3.7 |
|
Pannar |
2986 |
44.4 |
3.5 |
80.0 |
3.5 |
|
Pioneer |
6444 |
40.0 |
2.4 |
88.4 |
3.2 |
|
Pioneer |
6312 |
55.0 |
2.3 |
91.7 |
3.2 |
|
Croplan |
6N15 |
81.9 |
3.2 |
100.0 |
3.8 |
|
Croplan |
6N14 |
83.3 |
2.5 |
95.0 |
3.4 |
|
Resist check |
441x439 |
70.0 |
2.2 |
88.3 |
3.2 |
|
Susc check |
270 |
84.9 |
3.6 |
100.0 |
4.2 |
|
Resist check |
441x439 |
81.7 |
1.5 |
96.7 |
3.0 |
|
Susc check |
270 |
90.0 |
3.6 |
100.0 |
4.3 |
|
|
|
|
|
|
|
|
|
Mean |
61.8 |
2.9 |
93.3 |
3.3 |
|
|
C.V. (%) |
31.3 |
26.2 |
12.4 |
16.0 |
|
|
LSD (0.05) |
27.3 |
1.07 |
16.3 |
0.77 |
1Severity 0-5: 0 = no rot visible, 5 = head entirely disintegrated and fallen to the ground.
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