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 (7), 1985 and 1986 (1), 1987 (2), 1988 to 1991 (6), 1992 to 1993 (9), 1994 (12), 1994 to 1996 (4) have been published. A summary of the results from 1974 to 1994 has also been published (8).
The loss estimates for 1999 published here were solicited from: Bill Gazaway 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, 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. As recommended by Dr. Arvydas Grybauskas, University of Maryland, the Maryland soybean disease loss estimate was provided by Robert Mulrooney of Delaware. 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 1999 average soybean yield and acreage decreased from that reported in 1998 (6). In 1999, 447.7 million bushels were harvested from 17.6 million acres in 16 southern states. The overall average for the 16 reporting states was 24.1 bushels/acre. The overall average reported in 1998 was 27.5 bushels/acre. The 1999 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 1999 was 11.3 %, a slight decrease from the 11.53 % loss for 1998 (6). In 1999, Mississippi reported the greatest percent loss at 18.36%, followed by Louisiana at 17.30 %. Virginia reported the least at 4.20 % (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 1998 was greatest in Missouri with 18.36 million bushels and least in Florida with 0.04 million bushels. The total reduction in soybean yield due to diseases in the 16 southern states was 57.27 million bushels in 1999, down from 78.282 million bushels in 1998; partially due to lower production. The estimated dollar value of this loss was $286,350,000 (based on $5.00/bu).
In 1999, the highest estimated percent loss was caused charcoal rot 3.39% (22.39 million bushels) (Table 2 & 3). The soybean cyst nematode was the second most damaging pathogen effecting an estimated 2.19% yield loss (10.48 million bushels). The least reported disease was brown stem rot. Brown stem rot was not reported as occurring in any of the 16 southern states.
In 1999, 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 1999.
| State | Acres harvested | Yield/acre (bu) | Total production (bu) |
| Alabama | 200,000 | 16 | 3,200,000 |
| Arkansas | 3,400,000 | 27 | 91,800,000 |
| Delaware | 201,000 | 26 | 5,200,000 |
| Florida | 19,000 | 30 | 600,000 |
| Georgia | 180,000 | 18 | 3,200,000 |
| Kentucky | 1,100,000 | 19 | 20,900,000 |
| Louisiana | 1,010,000 | 25 | 20,900,000 |
| Maryland | 480,000 | 30 | 14,400,000 |
| Mississippi | 1,950,000 | 26 | 50,700,000 |
| Missouri | 5,300,000 | 27 | 143,100,000 |
| North Carolina | 1,300,000 | 23 | 29,900,000 |
| Oklahoma | 460,000 | 23 | 10,500,000 |
| South Carolina | 600,000 | 21 | 12,600,000 |
| Tennessee | 1,040,000 | 19 | 19,800,000 |
| Texas | 320,000 | 31 | 9,900,000 |
| Virginia | 460,000 | 24 | 11,000,000 | Total | 18,020,000 | Avg. =24.1 | 447,700,000 |
Table 2. Estimated percentage loss of soybean yields for 16 southern states during 1999 a.
|
Disease |
AL | AR | DE | FL | GA | KY | LA | MD | MS | MO | NC | OK | SC | TN | TX | VA | Avg. | |
|
Anthracnose |
3.00 | 0.48 | TR | 1.00 | 0.10 | 0.50 | 1.00 | TR | 0.40 | . | 0.08 | 0.30 | 1.00 | 0.20 | 3.00 | TR | 0.69 | |
|
Bacterial diseases |
TR | 0.01 | 0.00 | 0.00 | 0.00 | 0.01 | TR | 0.00 | TR | . | 0.00 | TR | 0.03 | 0.00 | 0.00 | 0.00 | 0.12 | |
|
Brown leaf spot |
0.00 | . | 0.00 | 0.00 | 0.00 | 0.10 | 0.00 | 0.00 | 0.10 | . | 0.00 | 0.00 | 0.10 | 0.20 | 0.20 | TR | 0.04 | |
|
Brown stem rot |
0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | . | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | |
|
Charcoal rot |
0.50 | 4.00 | 5.00 | 1.00 | 0.20 | 10.00 | 4.00 | 5.00 | 14.00 | 2.50 | 0.40 | 4.00 | 0.10 | 1.50 | 2.00 | 0.00 | 3.39 | |
|
Diaporthe/Phomopsis |
0.10 | 0.01 | TR | 2.00 | 0.40 | 0.20 | 1.00 | TR | TR | 0.25 | 0.10 | 0.30 | 0.01 | 0.00 | 1.00 | 1.00 | 0.40 | |
|
Downy mildew |
0.50 | 0.01 | 0.00 | 0.00 | 0.10 | 0.01 | TR | 0.00 | . | . | 0.00 | TR | 0.05 | 0.00 | 0.00 | 0.00 | 0.40 | |
|
Frogeye |
0.50 | 0.10 | 0.00 | 0.50 | 0.50 | 0.01 | 0.20 | 0.00 | 0.05 | . | 0.00 | 0.00 | 0.05 | 1.00 | 0.20 | TR | 0.19 | |
|
Fusarium wilt and rot |
TR | 0.01 | 0.00 | 0.00 | 0.00 | 0.01 | TR | 0.00 | . | 0.50 | 0.00 | 0.00 | 0.01 | 0.00 | 0.20 | TR | 0.05 | |
|
Other diseasesb |
0.00 | . | 0.00 | 0.00 | 0.40 | 0.00 | 0.20 | 0.00 | . | . | 5.05 | 0.00 | 0.00 | 0.00 | 0.10 | 0.00 | 0.36 | |
|
Phytophthora rot |
0.00 | 0.04 | 0.00 | 0.00 | 0.00 | 0.01 | 0.20 | 0.00 | 0.01 | 1.50 | 0.20 | 0.50 | 0.01 | 0.10 | 0.10 | TR | 0.17 | |
|
Pod & stem blight |
3.00 | 0.60 | TR | . | 0.10 | 0.20 | 2.00 | TR | 2.00 | . | 0.80 | 1.00 | 0.80 | 0.00 | 0.50 | TR | 0.69 | |
|
Purple seed stain |
0.40 | 0.25 | 0.00 | 0.10 | 0.10 | 0.01 | 3.00 | 0.00 | 0.70 | . | 0.01 | 0.40 | 0.25 | 0.00 | 1.00 | 0.00 | 0.39 | |
|
Aerial blight |
0.00 | 0.10 | 0.00 | 0.00 | 0.00 | 0.00 | 2.00 | 0.00 | . | . | 0.00 | 0.00 | 0.00 | 0.00 | 0.10 | 0.00 | 0.14 | |
|
Sclerotinia |
0.00 | . | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | TR | . | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | |
|
Seedling diseases |
0.20 | 1.00 | 0.50 | 1.00 | 0.60 | 0.10 | TR | 0.50 | 0.50 | 0.50 | 0.01 | 0.75 | 0.10 | 1.50 | 0.40 | 0.50 | 0.51 | |
|
Southern blight |
0.10 | 0.01 | 0.00 | 0.10 | 0.20 | 0.01 | TR | 0.00 | TR | . | 0.05 | TR | 1.25 | 0.10 | 0.20 | TR | 0.13 | |
|
Soybean cyst nematode |
2.00 | 1.25 | 3.00 | 1.00 | 3.00 | 2.00 | 1.00 | 3.00 | 0.10 | 2.50 | 5.70 | 1.50 | 3.00 | 4.00 | 0.00 | 2.00 | 2.19 | |
|
Root-knot nematode |
1.00 | 1.45 | TR | 0.10 | 3.00 | 0.00 | 2.00 | 0.00 | TR | 0.10 | 0.90 | 0.10 | 3.00 | 0.10 | 0.20 | 0.10 | 0.75 | |
|
Other nematodesc |
2.00 | 0.10 | 0.00 | . | 0.50 | 0.00 | 0.50 | 0.00 | 0.00 | . | 0.30 | 0.00 | 2.00 | 0.20 | 0.00 | 0.50 | 0.38 | |
|
Stem Canker |
0.00 | 0.25 | TR | 0.00 | 0.50 | 0.01 | TR | TR | TR | . | 0.00 | 0.00 | 0.00 | 0.10 | 0.10 | 0.00 | 0.06 | |
|
Sudden death syndrome |
1.00 | 0.10 | 0.00 | 0.00 | 0.00 | 0.01 | 0.00 | 0.00 | TR | 0.25 | 0.00 | 0.00 | 0.00 | 0.30 | 0.10 | 0.00 | 0.11 | |
|
Virusd |
TR | 0.04 | 0.00 | 0.00 | 0.10 | 0.10 | 0.20 | 0.00 | 0.50 | . | 0.20 | 0.10 | 1.50 | 0.00 | 0.10 | 0.10 | 0.18 | |
|
Total disease % |
14.30 | 9.81 | 8.50 | 6.80 | 9.80 | 13.29 | 17.30 | 8.50 | 18.36 | 8.10 | 13.80 | 8.95 | 13.26 | 9.30 | 9.50 | 4.20 | 11.34 |
a Rounding errors present. TR indicates trace.
b Other diseases listed were: ozone in NC, red crown rot caused by Cylindrocladium parasiticum in NC and VA; target spot in LA, and Phymatotrichum root rot in TX.
cOther nematodes listed were: Stubby root in VA; Columbia lance in NC and Georgia; Lance in LA; and Reniform in AL, AR, and NC.
d Viruses were identified as: soybean mosaic in AL, AR, GA, KY, MS, NC, and VA; bean pod mottle in AR, KY, LA, MS,NC, and VA; Tobacco ringspot in AR; and peanut mottle in VA.
Table 3. Estimated reduction of soybean yield (bushels in millions) for 16 southern states during 1999a
|
Disease |
AL | AR | DE | FL | GA | KY | LA | MD | MS | MO | NC | OK | SC | TN | TX | VA | Tot. |
|
Anthracnose |
0.11 | 0.49 | . | 0.01 | 0.00 | 0.12 | 0.25 | 0.00 | 0.25 | 0.00 | 0.03 | 0.03 | 0.15 | 0.04 | 0.33 | . | 1.81 |
|
Bacterial diseases |
. | 0.01 | 0.00 | 0.00 | 0.00 | 0.00 | . | 0.00 | . | 0.00 | 0.00 | . | 0.00 | 0.00 | 0.00 | 0.00 | 0.02 |
|
Brown leaf spot |
0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.02 | 0.00 | 0.00 | 0.06 | 0.00 | 0.00 | 0.00 | 0.01 | 0.04 | 0.02 | 0.00 | 1.83 |
|
Brown stem rot |
0.00 | . | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | . | 0.00 |
|
Charcoal rot |
0.02 | 4.07 | 0.29 | 0.01 | 0.01 | 2.41 | 1.01 | 0.79 | 8.69 | 3.89 | 0.14 | 0.46 | 0.01 | 0.33 | 0.22 | 0.00 | 22.34 |
|
Diaporthe/Phomopsis |
0.00 | 0.01 | . | 0.01 | 0.01 | 0.05 | 0.25 | 0.00 | . | 0.39 | 0.03 | 0.03 | 0.00 | 0.00 | 0.11 | 0.12 | 1.03 |
|
Downy mildew |
0.02 | 0.01 | 0.00 | 0.00 | 0.00 | 0.00 | . | 0.00 | . | 0.00 | 0.00 | . | 0.01 | 0.00 | 0.00 | 0.00 | 0.04 |
|
Frogeye |
0.02 | 0.10 | 0.00 | 0.00 | 0.02 | 0.00 | 0.05 | 0.00 | 0.03 | 0.00 | 0.00 | 0.00 | 0.01 | 0.22 | 0.02 | 0.00 | 0.47 |
|
Fusarium wilt and rot |
. | 0.01 | 0.00 | 0.00 | 0.00 | 0.00 | . | 0.00 | . | 0.78 | 0.00 | 0.00 | 0.00 | 0.00 | 0.02 | . | 0.80 |
|
Other diseases |
0.00 | . | 0.00 | 0.00 | 0.01 | 0.00 | 0.05 | 0.00 | . | 0.00 | 1.75 | 0.00 | 0.00 | 0.00 | 0.01 | . | 1.83 |
|
Phytophthora rot |
0.00 | 0.04 | 0.00 | 0.00 | 0.00 | 0.00 | 0.05 | 0.00 | 0.01 | 2.34 | 0.07 | 0.06 | 0.00 | 0.02 | 0.01 | 0.00 | 2.60 |
|
Pod & stem blight |
0.11 | 0.61 | . | . | 0.00 | 0.05 | 0.51 | 0.00 | 1.24 | 0.00 | 0.28 | 0.12 | 0.12 | 0.00 | 0.05 | . | 3.09 |
|
Purple seed stain |
0.01 | 0.25 | 0.00 | 0.00 | 0.00 | 0.00 | 0.76 | 0.00 | 0.43 | 0.00 | 0.00 | 0.05 | 0.04 | 0.00 | 0.11 | . | 1.66 |
|
Aerial blight |
0.00 | 0.10 | 0.00 | 0.00 | 0.00 | 0.00 | 0.51 | 0.00 | . | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.01 | 0.00 | 0.62 |
|
Sclerotinia |
0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | . | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
|
Seedling diseases |
0.01 | 1.02 | 0.03 | 0.01 | 0.02 | 0.02 | . | 0.08 | 0.31 | 0.78 | 0.00 | 0.09 | 0.01 | 0.33 | 0.04 | 0.06 | 2.81 |
|
Southern blight |
0.00 | 0.01 | 0.00 | 0.00 | 0.01 | 0.00 | . | 0.00 | . | 0.00 | 0.02 | . | 0.18 | 0.02 | 0.02 | . | 0.27 |
|
Soybean cyst nematode |
0.07 | 1.27 | 0.17 | 0.01 | 0.11 | 0.48 | 0.25 | 0.47 | 0.06 | 3.89 | 1.98 | 0.17 | 0.44 | 0.87 | 0.00 | 0.23 | 10.48 |
|
Root-knot nematode |
0.04 | 1.48 | . | 0.00 | 0.11 | 0.00 | 0.51 | 0.00 | . | 0.16 | 0.31 | 0.01 | 0.44 | 0.02 | 0.02 | 0.01 | 3.10 |
|
Other nematodes |
0.07 | 0.10 | 0.00 | . | 0.02 | 0.00 | 0.13 | 0.00 | . | 0.00 | 0.10 | 0.00 | 0.29 | 0.04 | 0.00 | 0.06 | 0.82 |
|
Stem Canker |
0.00 | 0.25 | . | 0.00 | 0.02 | 0.00 | . | 0.00 | . | 0.00 | 0.00 | 0.00 | 0.00 | 0.02 | 0.01 | 0.00 | 0.31 |
|
Sudden death syndrome |
0.04 | 0.10 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | . | 0.39 | 0.00 | 0.00 | 0.00 | 0.07 | 0.01 | 0.00 | 0.61 |
|
Virus |
. | 0.04 | 0.00 | 0.00 | 0.00 | 0.02 | 0.05 | 0.00 | 0.31 | 0.00 | 0.07 | 0.01 | 0.22 | 0.00 | 0.01 | 0.01 | 0.75 |
|
Total |
0.53 | 9.99 | 0.49 | 0.04 | 0.35 | 3.20 | 4.37 | 1.34 | 11.40 | 12.61 | 4.79 | 1.03 | 1.93 | 2.03 | 1.04 | 0.48 | 57.27 |
Literature Cited