1999 Georgia Plant Disease Loss Estimates (SB 41-02) University of Georgia Extension It is estimated that 1999 plant disease losses, including control costs, amounted to approximately $580.25 million. The value of the crops used in this estimate was $4.124 billion, resulting in a 14.07 percent total disease loss across all crops included in this summary. 2017-03-23 11:55:45.83 2006-06-02 14:35:37.0 1999 Georgia Plant Disease Loss Estimates | Publications | UGA Extension Skip to content

1999 Georgia Plant Disease Loss Estimates (SB 41-02)

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Compiled by: Jean L. Williams-Woodward,
Extension Plant Pathologist

It is estimated that 1999 plant disease losses, including control costs, amounted to approximately $580.25 million. The value of the crops used in this estimate was $4.124 billion, resulting in a 14.07 percent total disease loss across all crops included in this summary.

The estimated values for most crops used to compute these disease losses are summarized in: Georgia Agricultural Statistics Service, Georgia Farm Report Vol. 00, No. 4. Estimates for tobacco are based on Market News Service figures for growers' net sales and do not include warehouse resales. Estimates for vegetables, ornamentals and turf rely on specialists' knowledge of the industry and industry sources for information.

The Following Members of the University of Georgia Department of Plant Pathology Made Direct Contribution to this Publication:
Paul Bertrand Tifton, GA 912-386-7495
Phil Brannen Athens, GA 706-542-2685
Tim Brenneman Tifton, GA 912-386-3371
Ed Brown Athens, GA 706-542-2685
Albert Culbreath Tifton, GA 912-386-3370
Barry Cunfer Griffin, GA 770-412-4012
Richard Davis Athens, GA 706-542-2685
Taft Eaker Athens, GA 706-542-9146
David Langston Tifton, GA 912-386-7495
Dan Phillips Griffin, GA 770-412-4009
Harald Scherm Athens, GA 706-542-1258
Jean Williams-Woodward Athens, GA 706-542-9146

1999 Plant Disease Clinic Annual Summary

Extension Plant Pathology maintains three clinics as educational resources for county Extension agricultural faculty to use to aid their clients in diagnosing and correcting disease- and insect-related plant problems. Plant samples are submitted directly to the county Extension faculty who, at their discretion, forward samples to the appropriate clinic. Commercial turf, fruits, forage crops, greenhouse and ornamental nursery samples are sent to the Plant Disease Clinic in Athens. Diagnoses of and control recommendations for commercial samples of field crops, pecans and vegetables are handled by the Plant Disease Clinic at the Rural Development Center in Tifton, Georgia. All non-commercial plant samples are sent to the Homeowner IPM Clinic in Athens for disease and/or insect diagnoses and recommendations. Diagnoses and educational recommendations are returned to the county faculty. The clinics maintain a computerized database of samples and their diagnoses, as well as a reference library for use by Extension agents, specialists, researchers, and students.

As in 1998, ornamentals (trees, herbaceous and woody ornamentals) and turf comprised most of the samples received in 1999. The high number of turf samples is attributed to two factors: 1) early summer drought stress compounded in many cases by over-watering through the remainder of the summer, and 2) an unusually warm fall created ideal conditions for disease when warm season turfgrasses should have been going dormant.

Clinic Summaries: 1999 Plant Specimen Diagnosis
Crop Commercial Samples Homeowner IPM Clinic: Digital Imaging Samples Total
Disease Insect
Field Crops 181 92 273
Vegetables 360 121 19 231 731
Fruits & Nuts 66 48 11 67 192
Herbaceous Ornamentals 233 131 17 164 545
Woody Ornamentals 295 449 53 232 1029
Trees 149 147 42 163 501
Turf & Forages 583 613 14 124 1334
Miscellaneous 10 23 330 29 392
TOTAL 1877 1147 486 1102 4997


Apple producers experienced problems with several pathogens in 1999. Principle among these were fire blight and rots, and these diseases substantially reduced yield in some orchards. Cost of control included increased pesticide usage for both fire blight and summer rots. Often, chemical fungicides or antibiotic applications did not adequestely suppress disease. This indicates likely resistance buildup in pathogen populations; this is especially true for fire blight.

Disease % Reduction in Crop Value Damage
($ Thousands)
Cost of Control
($ Thousands)
($ Thousands)
Fire Blight 1.0 34.2 90.0 124.2
Bitter Rot 5.0 170.9 132.0 302.9
Bot Rot 3.0 102.5 91.0 193.5
Black Rot 2.0 68.4 60.0 128.4
Alternaria Leaf Spot 1.0 34.2 5.0 39.2
Powdery Mildew 0.3 10.3 22.0 32.3
Sooty Blotch 0.3 10.3 —¹ 10.3
Fly Speck 0.3 10.3 —¹ 10.3
Cedar Apple Rust 0.1 3.4 —¹ 3.4
Scab 0.1 3.4 1.0 4.4
Other Diseases 0.5 17.1 1.0 18.1
Total 13.6 465.0 402.0 867.0
1 Controlled with fungicides applied for other diseases.
Estimated by Phil Brannen, Extension Plant Pathologist.


With a total production of 11,000,000 pounds valued at $10.1 million, Georgia blueberry yields were up from 1998 but still below the long-term average. In rabbiteye cultivars, considerable yield losses occurred due to poor fruit set, a result of the low-chill winter in combination with spring drought and arthropod (thrips, gall midge) infestation. The incidence of mummy berry disease was below average, primarily because of the dry spring. Botrytis blight was essentially absent, as no predisposing freezes occurred during bloom. In southern highbush cultivars, problems due to foliar diseases and dieback increased compared with previous years, as did Phytophthora root rot (primarily in the production of nursery stock).

Disease % Reduction in
Crop Value
($ Thousands)
Cost of Control
($ Thousands)
($ Thousands)
Mummy Berry 1.5 151.2 350.0 501.2
Botrytis Blight <0.1 10.1 0.0 10.1
Foliar Disease 1.0 100.8 40.0 140.8
Dieback 1.0 100.8 0.0 100.8
Phytophthora Root Rot 0.3 30.2 10.0 40.2
Total 3.9 393.1 400.0 793.1
Estimate by Harald Scherm, Research Plant Pathologist; Phil Brannen, Extension Plant Pathologist

Bunch Grape

1999 Disease Loss Estimates for Bunch Grapes Are Not Available


Canola is an emerging agricultural commodity in Georgia and neighboring states. Acreage in Georgia has varied from more than 15,000 to fewer than 5,000 in recent years, depending on market prices and weather at planting time. Disease losses from the potentially most devastating disease, blackleg, have been kept well below 5 percent by moving production to new areas where the disease is not established and limited use of moderately resistance cultivars. Ample seed supplies of a highly resistant cultivar were available for the 1999-2000 crop, but only a few hundred acres were planted across the southeastern United States. Yield losses from Sclerotinia stem rot were well below 5 percent due to an extremely dry 1999-2000 season. Foliar and pod diseases were present at very low levels and did not reduce yields. Overall disease losses for the 1999-2000 season were well below 5 percent.

Canola Diseases Found in Georgia
Disease Pathogen % Reduction
in Crop Value
Black Leg Leptosphaeria maculans <5.0
Sclerotinia Stem Rot Sclerotinia sclerotiorum <5.0
Alternaria Black Spot Alternaria brassicicola & A. brassicae 0.0
White Leaf Spot Pseudocercosporella capsellai 0.0
Downy Mildew Peronospora parasitica 0.0
Powdery Mildew Erysiphe cruciferarum 0.0
Damping Off Rhizoctonia solani & Pythium sp. 0.0
Total <5.0


Drought caused significant damage to the 1999 corn crop in Georgia, though not as much as to the 1998 crop. Approximately 350,000 acres were planted, but only 300,000 acres were harvested, with statewide yields averaging 105 bu/A. The total crop value in Georgia was estimated at $69,525,000. Aflatoxin levels were slightly lower than average in the 1999 corn crop, causing an estimated $4,172,000 in losses. Damage from nematodes was less than in 1998. The hot, dry weather reduced foliar disease problems.

Disease % Reduction in
Crop Value
($ Millions)
Cost of Control
($ Millions)
($ Millions)
Root & Stalk Rot 0.1 0.07 0.0 0.07
Nematodes 2.5 1.74 1.0 2.74
Mycotoxins 6.0 4.17 0.0 4.17
Leaf Diseases 5.0 3.48 0.0 3.48
Total 13.6 9.46 1.0 10.46
Estimate by Richard Davis, Extension Nematologist


Approximately 1,470,000 acres of cotton were planted in 1999, but only 1,300,000 acres were harvested. Severe drought in many areas caused significant yield loss and even caused the complete loss of some acreage. Statewide average yields of 580 pounds of lint per acre were similar to 1998 but lower than in other recent years. Low prices reduced the total crop value for Georgia to an estimated $341,381,000, which was lower than recent years. Losses to boll rot were much lower than in 1998. Damage from nematodes was similar to recent years, though much of the damage was difficult to distinguish from drought damage: nematode-damaged root systems were less able to take up water, so the effect of drought conditions was more severe. Dry weather following planting reduced seedling disease levels.

Disease % Reduction in
Crop Value
($ Millions)
Cost of Control
($ Millions)
($ Millions)
Boll Rot (lint) 5.0 17.07 0.0 17.07
Nematodes 5.0 17.07 11.13 28.2
Seedling Disease 1.0 3.41 2.5 5.91
Fusarium Wilt 0.5 1.71 0.0 1.71
Total 11.5 39.26 13.63 52.89
Estimate by Richard Davis, Extension Plant Nematologist

Muscadine Grape

1999 Disease Loss Estimates for Muscadine Grape Are Not Available


The ornamental industry comprises greenhouse and floriculture crop production, container and field-grown nursery crop production, and commercial landscaping. It had an estimated economic value of $991 million in Georgia in 1999. Root rot diseases accounted for the largest percentage of disease loss in ornamentals as a result of excessive heat stress on roots in containerized nursery production. Powdery mildew infection was increased over 1998 largely due to warmer, humid summer conditions. Drought conditions through much of the state resulted in reduced losses from foliar diseases.

Disease % Reduction in
Crop Value
($ Millions)
Cost of Control
($ Millions)
($ Millions)
Bacterial diseases
(fire blight, leaf spots)
0.1 0.99 0.1 1.09
Fungal leaf spots, branch and stem cankers 1.0 9.91 6.8 16.71
Root and crown rots 3.0 29.73 5.1 34.83
Powdery mildew 0.3 2.97 0.9 3.87
Botrytis blight 0.2 1.98 1.0 2.98
Virus (TSWV, INSV, CMV) 0.2 1.98 0.0 1.98
Minor diseases (rust, downy mildew, nematode) 0.1 0.99 0.0 0.99
Total 5.1 48.55 18.1 62.45
Estimate by Jean Williams-Woodward, Extension Plant Pathologist


Peach production in 1999 (105,000,000 lbs. valued at $39.2 million) was almost twice that of 1998. Small fruit size was compensated for by excellent color and quality. Despite the relatively dry spring, considerable scab pressure developed, leading to unanticipated qualitiy problems. Brown rot incidence was very low in early-maturing cultivars but picked up as the season progressed and rains became more frequent. Bacterial spot was essentially absent due to dry spring weather. Problems with Armillaria root rot, for which there are currently no effective controls, increased.

Cost of control included cost of pesticides, equipment and labor. Costs associated with certain cultural practices (flail mowing to reduce gummosis, detailed pruning for control of Phomopsis shoot blight) are directly related to disease control and were, therefore, considered in the assessment.

Disease % Reduction in
Crop Value
($ Millions)
Cost of Control
($ Millions)
($ Millions)
Brown Rot 8.0 3.13 1.0 4.13
Scab 6.0 2.35 1.0 3.35
Bacterial Spot <0.1 0.03 0.01 0.04
Gummosis 0.2 0.08 0.02 0.10
Phomopsis Shoot Blight 0.1 0.04 0.01 0.05
Armillaria Root Rot 0.1 0.04 0.0 0.04
Total 14.5 1.627 2.79 7.71
Estimate by Harald Scherm, Research Plant Pathologist; Phil Brannen, Extension Plant Pathologist


The 1999 Georgia peanut crop was about normal for recent years with 546,000 acres harvested and an average yield of 2,600 lb/A. The total crop value was $386 million. Although there were heavier localized rains in July that resulted in some early disease pressure, most of the state had relatively dry conditions. Leaf spot losses were very low, and white mold pressure was significantly less than in 1998. Cylindrocladium black rot was somewhat reduced also, but there was more present at harvest than was evident earlier in the year. The University of Georgia TSWV Risk Index has been widely implemented, and estimated losses for that disease were the same as in 1998. There were some seed quality and stand establishment problems, particularly in early planted peanuts subjected to the cold temperatures in late April. This caused an increase in losses to seedling disease, and actual losses were probably higher due to the incidence of TSWV that no doubt resulted from the sparse stands.

Disease % Reduction in
Crop Value
($ Millions)
Cost of Control
($ Millions)
Leaf spots 1.0 3.9 40.0 43.9
White mold 4.0 15.4 20.0 35.4
Limb Rot 2.0 7.7 1 7.7
Pod Rot 1.0 3.9 2 3.9
Nematodes 3.0 11.6 8.0 19.6
Cylindrocladium Black Rot 2.0 7.7 1.0 8.7
Seedling Disease 2.0 7.7 0.5 8.2
Aspergillus Crown Rot 0.2 0.8 0.0 0.8
Tomato Spotted Wilt 4.5 17.4 0.03 17.4
Total 19.7 76.1 69.5 145.6
1 Folicur or Montero/Moncut treatment costs about $16/acre. Many growers made 2-4 applications of these or Abound for white mold, limb rot and leaf spot. About costs about twice as much, but only two applications are required.
2 The cost of gypsum treatments applied to reduce pod rot has not been estimated.
3 Additional costs for use of increased seeding rates for management of TSWV have not been calculated.
Estimate by Tim Brenneman and Albert Culbreath, Research Plant Pathologists

Status and Revision History
Published on Nov 17, 2004
Re-published on Feb 9, 2009
Re-published on Apr 30, 2009
Reviewed on Sep 1, 2012