2008 Georgia Plant Disease Loss Estimates (AP 102-1) University of Georgia Extension It is estimated that losses due to plant diseases in Georgia in 2008 amounted to $612.06 million. These losses include actual losses in yield and quality as well as costs of disease control measures. The value of these crops was approximately $4,846.05 million, which resulted in a 12.03% total disease loss for crops grown in 2008. 2016-11-29 14:35:32.763 2009-12-04 09:48:25.0 2008 Georgia Plant Disease Loss Estimates | Publications | UGA Extension Skip to content

2008 Georgia Plant Disease Loss Estimates (AP 102-1)

Download PDF
line drawing of row crop

David B. Langston, Jr.
Extension Plant Pathologist

It is estimated that losses due to plant diseases in Georgia in 2008 amounted to $612.06 million. These losses include actual losses in yield and quality as well as costs of disease control measures. The value of these crops was approximately $4,846.05 million, which resulted in a 12.03% total disease loss for crops grown in 2008.

The estimated values for most crops used to compute these disease losses were taken from the Georgia Agricultural Statistics Service Farm Report for 2008 and the 2008 Georgia Farm Gate Value Report. Actual disease estimates are made by specialists assigned to each crop and are based on reports and observations made each year. The information in this publication was compiled by David Langston, Extension vegetable pathologist. The following members of the University of Georgia department of Plant Pathology made direct contributions to this publication.

Phil Brannen Athens, GA 706-542-1250 pbrannen@uga.edu
Paul Bertrand Tifton, GA 229-386-7495 bertrand@uga.edu
Jason Brock Tifton, GA 229-386-7495 jbrock@uga.edu
Robert Kemerait Tifton, GA 229-386-7495 kemerait@uga.edu
David Langston Tifton, GA 229-386-7495 dlangsto@uga.edu
Alfredo Martinez Griffin, GA 770-228-7375 martinez@griffin.uga.edu
Holly Thornton Athens, GA 706-542-8987 hthornto@uga.edu
Jean Williams-Woodward Athens, GA 706-542-9140 jwoodwar@uga.edu

2007 Plant Disease Clinics Annual Summary

Extension Plant Pathology maintains two plant disease clinics as educational resources for county Extension agricultural faculty to use to aid their clients in diagnosing and correcting disease-related plant problems. The Athens Plant Disease Clinic, which includes the Homeowner IPM plant disease clinic, was operated by Holly Thornton. The following plant disease samples are processed in Athens: commercial fruit, ornamentals and turf; Christmas trees and forestry; all homeowner samples; legume forages and small grains; urban ornamental landscapes; and mushrooms and wood rots. There is a $10 processing fee for all physical homeowner samples submitted to the diagnostic clinic in Athens.

In Tifton, the Plant Disease Clinic is run by Jason Brock in the Horticulture Building on the main Tifton Campus - Room 116, 4604 Research Way. Diagnoses of and control recommendations for commercial samples of field crops, grain forages, pecans and vegetables are handled at this location.

Sample numbers continue to increase each year (1530 samples in 2007). This increase was seen in both homeowner and commercial sample submission, with the greatest increases occurring in commercial fruit sample submission and both homeowner and commercial turf submission. Last year was a very dry year and many of the problems seen were not disease-related but rather environmental or cultural-type plant problems.

Diagnoses and educational recommendations are returned to the county faculty. The clinics maintain a computerized database of samples and their diagnoses through the DDDI system, as well as a reference library for use by Extension agents, specialists, researchers and students. Monthly homeowner reports are also available via our departmental clinic homepage (http://www.plant.uga.edu/Extension/Clinics/PDC.htm).

Clinic Summaries: 2007 Plant Sample Submission
Crop Commercial Samples Homeowner IPM Samples Total
Field Crops 237 0 237
Vegetables 296 60 356
Fruits & Nuts 165 40 205
Herbaceous Ornamentals 102 38 140
Woody Ornamentals 128 107 235
Trees 71 110 181
Turf 434 241 675
Miscellaneous 7 15 22
Total 1,440 611 2,051

Apple

This was one of the driest years on record for north Georgia. As a result, disease losses were minimal for apple production. Due to extreme drought conditions, fire blight and summer rot diseases had a minimal impact. Absolutely no disease was recorded in untreated research apples at the Blairsville substation. Overall disease pressure was very low in apples. There is still a strong need for more efficacious fungicides for control of bitter rot and other summer rot diseases. In addition, though not yet observed, we are concerned that streptomycin antibiotic resistance may yet become an issue; currently, streptomycin is the only effective antibiotic for fire blight. If we lose this antibiotic due to resistance, apple production will be much more difficult. Cost of control included pesticide usage for fire blight, pruning costs and summer rot control measures.

Disease* % Reduction
in Crop Value
Damage
($Thousands)
Cost of Control
($ Thousands)
Total
($ Thousands)
Fire Blight 0.0 0.0 70.0 70.0
Bitter Rot 1.0 45.3 100.0 145.3
Bot Rot 0.0 0.0 52.0 52.0
Black Rot 0.0 0.0 33.0 33.0
Alternaria Leaf Spot 0.0 0.0 0.0 0.0
Powdery Mildew 0.1 4.5 11.5 16.0
Sooty Blotch 0.0 0.0 0.0 0.0
Fly Speck 0.0 0.0 0.0 0.0
Cedar Apple Rust 0.1 4.5 0.0 4.5
Scab 0.0 0.0 0.0 0.0
Other Diseases 0.1 5.3 1.0 3.3
Total 1.3 56.6 267.5 324.1

*Controlled with fungicides applied for other diseases.

Estimate by Phil Brannen, Extension Plant Pathologist

Blueberry

Blueberry production in 2008 was generally good to excellent. Due to extreme drought conditions, very few fungal diseases were observed. Powdery mildew was one of the few exceptions, and this was the first time in recent memory in which this disease was extensively observed. Rust was also prevalent in some locations, and Exobasidium leaf and fruit spot were identified in one or two locations as well. Bacterial leaf scorch, a newly identified bacterial disease of southern highbush blueberries, was observed in numerous locations throughout the blueberry belt, and it is now causing extensive losses on several varieties. Also, the viral disease red ring spot was identified at several sites, as well as yet another newly identified disease, necrotic ring blotch. Necrotic ring blotch is likely caused by a virus, but ongoing research has not yet firmly established the cause. It is becoming firmly established among some southern highbush varieties, where it results in early and complete defoliation. Until recently, blueberry viruses had been occasionally-observed curiosities, but they are rapidly becoming established threats to the industry.

Disease % Reduction
in Crop Value
Damage
($ Thousands)
Cost of Control
($ Thousands)
Total
($ Thousands)
Mummy Berry 0.1 70.6 1277.5 1348.1
Botrytis Blight 0.0 0.0 511.0 511.0
Foliar Disease 0.1 70.6 383.3 453.9
Rots 0.1 70.6 127.8 198.4
Bacterial Scorch 0.1 70.6 0.0 70.6
Dieback 0.1 70.6 127.8 198.4
Phytophthora Root Rot 0.1 70.6 127.8 198.4
Total 0.6 423.6 2555.0 2978.6
Estimate by Phil Brannen, Extension Plant Pathologist

Bunch Grape

Grape diseases were radically reduced by extreme drought. With the exception of powdery mildew, a dry weather fungal pathogen, disease pressure from fungi was virtually nonexistent, largely as a result of a dry year. Powdery mildew was prevalent in some locations, especially where poor fungicide programs were utilized. North Georgia is on the southern edge of the region where one can effectively grow wine grapes, and this is related to Pierce’s disease, a bacterial disease which is vectored by an insect, the glassy-winged sharpshooter. Cold winter temperatures either kill the insect, which transmits the disease, or the temperatures may actually prevent the bacteria from surviving, but the verdict is still out on which is most important. However, we do know that cold temperatures allow for production of Vinifera wine grapes, and we do not recommend that producers plant these at elevations below 1,300 feet. As a result of warmer winters, we have observed substantial increases in vine death, even at higher elevations and longitudes. In some cases, producers have gone from losing less than10 vines per year to losses of several hundred vines, as observed in 2006 and 2007. Pierce’s disease losses were once again extensive in 2008; however, the colder winter of 2007/2008, combined with more aggressive insect management for Pierce’s disease vectors, likely resulted in reduced losses as compared to the previous two years. Crown gall, another bacterial disease associated with plant injury, increased due to freeze damage observed in 2007.

Disease % Reduction
in Crop Value
Damage
($ Thousands)
Cost of Control
($ Thousands)
Total
($ Thousands)
Botrytis 0.1 2.1 40.0 42.1
Downy Mildew 0.1 2.1 70.0 72.1
Black Rot 0.1 2.1 70.0 72.1
Powdery Mildew 2.0 41.1 20.0 61.1
Phomopsis Cane Blight 1.0 20.6 35.0 55.6
Crown Gall 0.2 4.1 5.0 9.1
Pierce’s Disease 0.5 10.3 30.0 40.3
Total 4.0 82.3. 270.0 352.3
Estimate by Phil Brannen, Extension Plant Pathologist

Corn

In 2008, corn for grain was planted on 370,000 acres and was harvested from 310,000 acres in Georgia with an average yield of 140 bu/A. The 2008 crop was valued at $199.64 million. Southern rust (Puccinia polysora) was a significant problem for many corn growers in 2008 and was especially damaging to the corn crop planted after harvest of wheat. Additionally, a second virulent race of P. polysora was confirmed in Georgia in 2008 to overcome the resistance to southern rust in hybrids (the rpp9 gene). Rainfall was less abundant during the 2005 and 2006 growing seasons than in 2003 and 2004. In addition to southern corn rust, northern corn leaf blight (Exserohilum turcicum) was also quite severe in many fields. The 2008 season was the first time in recent years that this disease was observed with such severity and widespread incidence. Use of fungicides, especially strobilurin chemistries, was common in 2008. The true importance of damage from nematodes (e.g. sting, stubby root and southern root-knot nematodes) is becoming more apparent as growers and county agents become more familiar with the symptoms.

Disease % Reduction
in Crop Value
Damage
($ Millions)
Cost of Control
($ Millions)
Total
($ Millions)
Root & Stalk Rot 0.1 0.2 0.0 0.2
Nematodes 5.0 10.0 0.8* 10.8
Mycotoxins 4.0 8.0 0.0 8.0
Southern Corn Rust 5.0 10.0 1.5** 11.5
Northern Corn Leaf Blight 0.5 1.0 —** 1.0
Other Leaf Diseases Trace 0.0 0.0
Total 14.6 29.2 2.3 31.5

*It is estimated that approximately 40,000 acres of corn were treated with 7 lb/A Counter insecticide-nematicide for control of nematodes.
**It is estimated that 100,000 acres of corn were sprayed with fungicides at least once during the 2008 season at a cost of $5/A for application and $10/A for cost of fungicide.

Estimate by Robert Kemerait, Extension Plant Pathologist

Cotton

In 2008, it was reported that cotton was planted on an estimated 940,000 acres and harvested from an estimated 920,000 acres. The average lint yield was 835 lb/A. The crop was valued at $498.728 million. Losses to seedling disease, primarily Rhizoctonia seedling blight, or “soreshin,” were moderate in 2008. The most serious disease in 2008 was Stemphylium leaf spot. Though this disease typically has its basis in a nutrient deficiency, especially potassium, the fungal pathogen is the cause of the leaf spots that can lead to rapid and severe defoliation in a field. Dry weather during 2008 may have affected the uptake of the potassium leading to the problems with Stemphylium leaf spot. Losses to nematodes, primarily southern root-knot nematodes, continue to be one of the most important problems for cotton growers in Georgia. Until growers are able to practice effective crop rotation and increase the number of years between cotton crops in a field, the losses and damage from parasitic nematodes will continue to increase unless growers use nematicides effectively. The current decline in cotton acreage in Georgia should make it easier for growers, especially those who grow peanuts, to increase the time between successive cotton crops in a field.

Disease % Reduction
in Crop Value
Damage
($ Millions)
Cost of Control
($ Millions)
Total
($ Millions)
Boll Rot (lint) 2.0 10.0 0.0 10.0
Nematodes 10.0 50.0 9.5a 59.5
Southern Root-knot 7.5 37.4
Reniform 2.0 10.0
Columbia Lance 0.5 2.6
Seedling Disease 1.0 5.0 1.2b 6.2
Fusarium Wilt Trace
Ascochyta Blight Trace
Stemphylium Leaf Spot 3.0 15.0 0.9c 15.9
Total 16.0 80.0 11.6 91.6

a This figure is based upon an estimation that approximately 35% of the cotton acreage in the state is treated with a nematicide rate of Temik (5 lb/A or greater), 20% with AVICTA Complete Pak, and approximately 2.0% of the acreage was treated with Telone II.
b This figure is an estimate of the cost of fungicides, both in the seed treatments and additional hopper box and in-furrow applications, that are used to manage seedling diseases. For this figure, it is estimated that approximately 15% of the cotton acreage in Georgia is treated with a fungicide in addition to the seed treatment to manage seedling disease.
cThis figure is based upon an estimate that 10% of the cotton acreage in the state was sprayed with a fungicide in 2008 to manage foliar diseases of cotton.

Estimate by Robert Kemerait, Extension Plant Pathologist

Muscadine Grape

Minimal disease pressure was observed in most muscadine vineyards due to extreme drought. Some losses continued to occur from “dead arm” diseases, but in general, disease losses were minimal. As a native grape, muscadines generally have less disease pressure than European grapes.

Disease* % Reduction
in Crop Value
Damage
($ Thousands)
Cost of Control
($ Thousands)
Total
($ Thousands)
Bitter Rot 0.1 2.0 40.2 42.2
Macrophoma Rot 0.1 2.0 35.0 37.0
Ripe Rot 0.1 2.0 15.0 17.0
Angular Leaf Spot 0.1 2.0 5.0 7.0
Black Rot 0.1 2.0 0.0 2.0
Phomopsis Dead Arm 0.1 2.0 1.0 3.0
Total 0.6 11.9 96.2 108.1

*Controlled with fungicides applied for other diseases.

Estimate by Phil Brannen, Extension Plant Pathologist

Peach

Peach production was good to excellent in 2008. Due to extremely dry conditions, brown rot and scab diseases were of minimal consequence on the fruit that remained. Likewise, bacterial diseases were of minimum consequence as well. However, many orchards were prematurely defoliated as a result of rust. Armillaria continued to be a major, expanding problem in replant peach production.

Disease % Reduction
in Crop Value
Damage
($ Thousands)
Cost of Control
($ Thousands)
Total
($ Thousands)
Brown Rot 0.1 19.7 1,750.0 1769.7
Scab 0.01 2.0 1,110.0 1112.0
Bacterial Spot 0.01 2.0 20.0 22.0
Phony Peach 0.5 98.3 230.0 328.3
Gummosis 0.1 19.7 20.0 39.7
Armillaria Root Rot 1.0 196.7 50.0 246.7
Phomopsis Constriction Canker 0.01 2.0 10.0 12.0
Total 1.7 340.2 3190.0 3530.2
Estimate by Phil Brannen, Extension Plant Pathologist

Peanut

In 2008, peanuts were planted on approximately 690,000 acres and harvested from approximately 685,000 acres. Yields in 2008 averaged 3,400 lb/A for a total production valued at $475.116 million. Tomato spotted wilt was very light again in 2008 for reasons that remain unclear. Severity of spotted wilt was much lower in 2006 (2.5% estimated reduction in crop value), 2007 (1.5% estimated reduction in crop value) and in 2008 than in 2005. Warm soil conditions early in the 2008 season favored the development of white mold ,which was the most important peanut disease for Georgia last year. Early and late leaf spot diseases were a problem for some growers and were especially severe in fields where peanuts were planted on a short rotation. As the popular fungicide tebuconazole became available in generic formulations, growers using the generic formulations were able to realize less expensive fungicide programs.

Disease % Reduction
in Crop Valuea
Status and Revision History
Published on Dec 4, 2009
Reviewed on Nov 26, 2012