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SOUTHERN UNITED STATES SOYBEAN DISEASE LOSS ESTIMATE FOR 2000
Compiled by Stephen R. Koenning Extension Specialist, Department of Plant Pathology, Campus Box
7616, North Carolina State University, Raleigh, NC 27695-7616
Since 1974, soybean disease loss estimates for the Southern United States have been published in the
Southern Soybean Disease Workers Proceedings. Summaries of the results from 1977 (6), 1985 and
1986 (2), 1987 (3), 1988 to 1991 (5), 1992 to 1993 (8), 1994 to 1996 (4) have been published. A
summary of the results from 1974 to 1994 for the Southern United States was published (7) in 1995,
and the soybean losses from disease for the top ten producing countries of 1994 was published in
1997(9). An estimate of soybean losses to disease from 1996-1998 is expected to be published in
2001(10).
The loss estimates for 2000 published here were solicited from: Edward Sikora in Alabama, Clifford
Coker in Arkansas, Robert Mulrooney in Delaware, Tom Kucharek in Florida, Richard Davis in
Georgia, Don Hershman in Kentucky, Ken Whitam in Louisiana, Arvydas Grybauskas in Maryland,
Gabe Sciumbato in Mississippi, Allen Wrather in Missouri, Steve Koenning in North Carolina, Phil
Pratt in Oklahoma, Charles Drye in South Carolina, Melvin Newman in Tennessee, Joseph Krausz in
Texas, and Patrick Phipps in Virginia. Various methods were used to obtain the disease losses, and
most individuals used more than one. The methods used were: field surveys, plant disease diagnostic
clinic samples, variety trials, questionnaires to Cooperative Extension staff, research plots, grower
demonstrations, private crop consultant reports, and foliar fungicide trials. The actual production
figures for each state were supplied by the state crop reporting services. Production losses were based
on estimates of yield in the absence of disease. The formula was: potential production without disease
loss = actual production ¸ 1-percent loss (decimal fraction).
In the southern states, the 2000 average soybean yield increased and acreage decreased from that
reported in 1999 (1). In 2000, 509.8 million bushels were harvested from 17.1 million acres in 16
southern states. The overall average for the 16 reporting states was 28.7 bushels/acre. The overall
average reported in 1999 was 24.1 bushels/acre. The 2000 total acres harvested, average yield in
bushels per acre, and total production in each state are presented in Table 1.
Percentage loss estimates from each state are specific as to causal organism or the common name of
the disease (Table 2). The total average percent disease loss for 2000 was 9.4 %, a substantial
decrease from the 10.54 % loss for 1999 (1). In 2000, Louisiana reported the greatest percent loss at
17.1 %, followed by Mississippi at 14.20 %. Delaware, Maryland, and Virginia reported the least at
3.0 %, 4.0 %, and 5.0 %, respectively (Table 2).
The estimated reduction of soybean yields is specific as to the causal organism or the common name
of the disease (Table 3). The estimated reduction in soybean yield due to diseases during 2000 was
greatest in Missouri with 14.3 million bushels and least in Florida with 0.03 million bushels. The total
reduction in soybean yield due to diseases in the 16 southern states was 53.55 million bushels in 2000,
down from 57.27 million bushels in 1999. The decrease in losses on a relatively large crop may be in
response to fewer acres planted resulting lower losses from soilborne diseases. The estimated dollar
value of this loss was $267,800,000 (based on $5.00/bu).
In 2000, the highest estimated percent loss was caused charcoal rot 2.27% (15.55 million bushels)
(Tables 2 & 3). The soybean cyst nematode was the second most damaging pathogen effecting an
estimated 2.23 % yield loss (14.6 million bushels). The least reported disease was brown stem rot.
Brown stem rot was reported as occurring in Kentucky and Virginia only of the 16 southern states.
In 2000, diseases continued to cause significant loss in soybean production throughout the 16 southern
states that participated in this disease loss estimate. It is essential that Extension and University
research continue their efforts to discover methods to control these diseases and to educate soybean
producers concerning the best methods to prevent yield loss due to soybean diseases.
Table 1. Soybean production for 16 southern states in 2000.
State Acres harvested Yield/acre (bu) Total production (bu)
Alabama
160,000
17
2,700,000
Arkansas
3,325,000
24
79,800,000
Delaware
221,000
44
9,700,000
Florida
15,000
27
400,000
Georgia
180,000
24
4,300,000
Kentucky
1,080,000
40
43,200,000
Louisiana
916,000
20.5
18,800,000
Maryland
490,000
41
20,100,000
Mississippi
1,620,000
21
34,000,000
Missouri
5,100,000
36
184,000,000
North Carolina
1,330,000
31
41,200,000
Oklahoma
325,000
15
4,900,000
South Carolina
450,000
24
10,800,000
Tennessee
1,160,000
26
30,200,000
Texas
260,000
30
7,800,000
Virginia
460,000
39
17,900,000
Total
17,092,000
Avg. =28.7
509,800,000