2009 Georgia Plant Disease Loss Estimates (AP 102-2) University of Georgia Extension It is estimated that 2009 plant disease losses, including control costs, amounted to approximately $653.06 million. The value of the crops used in this estimate was approximately $5887.33 million, resulting in an 11.09 total percent disease loss across all crops included in this summary. 2016-07-22 16:27:07.353 2010-11-08 16:03:54.0 2009 Georgia Plant Disease Loss Estimates | Publications | UGA Extension Skip to content

2009 Georgia Plant Disease Loss Estimates (AP 102-2)

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Compiled by: Jean Williams-Woodward,
Extension Plant Pathologist


It is estimated that 2009 plant disease losses, including control costs, amounted to approximately $653.06 million. The value of the crops used in this estimate was approximately $5887.33 million, resulting in an 11.09 total percent 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, Volume 10-No. 1, the 2009 Georgia Farm Gate Value Report (AR-10-01), and 2009 Georgia Farm gate Fruits and Nuts Report (AR 10-04). Some estimates for fruits, 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:
Phil Brannen Athens, GA 706-542-2685 pbrannen@uga.edu
Jason Brock Tifton, GA 229-386-7202 jborck@uga.edu
Robert Kemerait Tifton, GA 912-386-7495 kemerait@uga.edu
David Langston Tifton, GA 912-386-7495 dlangston@uga.edu
Alfredo Martinez Griffin, GA 770-228-7375 martinez@griffin.uga.edu
Byron Candole Athens, GA 706-542-4719 bcandole@uga.edu
Jean Williams-Woodward Athens, GA 706-542-9140 jwoodwar@uga.edu

2009 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, is operated by Byron Candole and Jan Fowler and is located in 2405 Miller Plant Science Building. Commercial fruit, ornamentals and turf; Christmas trees and forestry; all homeowner samples; and legume forages, small grains, mushroom identification and wood rots are processed in the Athens Plant Disease Clinic. There is a $10 processing fee for all physical homeowner samples. There is no charge for commercial physical samples or digital diagnostic samples. Dr. Elizabeth Little joined Extension pathology in 2009 and is responsible for homeowner IPM sample recommendations.

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

Commercial sample numbers continue to increase each year (1,440 samples in 2008); however, overall sample numbers were down compared to 2008 (2,051 samples in 2008) because the homeowner clinic was closed and not receiving samples for much of the year due to personnel loss. The greatest increase in sample submission over 2008 was seen in commercial vegetables. Last year was very dry 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. Monthly homeowner reports are also available via our departmental clinic homepage (http://www.plant.uga.edu/Extension/Clinics/PDC.htm).

 

CLINIC SUMMARIES: 2009 PLANT SAMPLE SUBMISSION
Crop Commercial
Samples
Homeowner
IPM Samples
Total
Field Crops 168 0 168
Vegetables 412 51 463
Fruits & Nuts 137 16 153
Herbaceous Ornamentals 140 20 160
Woody Ornamentals 130 77 207
Trees 86 47 133
Turf 481 132 613
Miscellaneous 6 12 18
Total 1,560 355 1,915

APPLE

The 2009 season was very wet for north Georgia. In one research trial, rain was recorded for 71 of 147 days in the trial. As a result, disease losses were relatively high for apples, but generally less than expected in commercial plantings. Fire blight was not prevalent, since early-season conditions were generally too cold, though rainfall was adequate. Summer rot diseases were prevalent, and bitter rot, as well as flyspeck and sooty blotch, did result in production losses. Overall disease pressure was moderate. There is still a strong need for more efficacious fungicides, especially 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 1.0 72.4 80.0 152.4
Bitter Rot 5.0 361.9 100.0 461.9
Bot Rot 0.1 7.2 52.0 59.2
Black Rot 0.1 7.2 33.0 40.2
Alternaria Leaf Spot 0.1 7.2 0.0 7.0
Powdery Mildew 0.1 7.2 11.5 18.7
Sooty Blotch 0.1 7.2 1.0 7.2
Fly Speck 0.1 7.2 0.0 7.2
Cedar Apple Rust 0.01 0.7 0.0 0.7
Scab 0.01 0.7 0.0 0.7
Other Diseases 0.1 0.7 1.0 1.7
Total 6.6 479.9 277.5 757.4
* Controlled with fungicides applied for other diseases.

Estimate by Phil Brannen, Extension Plant Pathologist

BLACKBERRY

Blackberries are a relatively new commodity for Georgia. Diseases have been of major consequence to losses observed, and limited research information is available for this expanding market. In 2009, cane blight caused significant damage in many locations. This disease is especially damaging when wet weather follows pruning operations. Viruses, many of which can?t be readily detected, continue to make their way into the state and have also caused significant losses. Botrytis (gray mold) was also prevalent due to rainy weather, but fungicidal applications generally decreased losses to low levels relative the total crop.

Disease % Reduction
in Crop Value
Damage
($ Thousands)
Cost of Control
($ Thousands)
Total
($ Thousands)
Botrytis 5.0 472.8 1,091.9 1,564.7
Orange Rust 0.01 0.9 136.5 137.4
Cane and Leaf Rust 0.1 9.5 546.0 555.4
Double Blossom 0.1 9.5 273.0 282.4
Viruses 5.0 472.8 136.5 609.3
Phytophthora Root Rot 0.1 9.5 27.3 36.8
Cane Blight 5.0 472.8 273.0 745.8
Septoria Leaf Spot 0.1 9.5 109.2 118.6
Botryosphaeria 1.0 94.6 136.5 231
Total 16.4 1,551.7 2,729.8 4,281.5

Estimate by Phil Brannen, Extension Plant Pathologist

BLUEBERRY

Blueberry production in 2009 was generally good, but excessive rainfall resulted in losses to molds that are generally not blueberry pathogens; surface molds, such as Cladosporium and yeasts, were observed on overripe fruit that could not be harvested due to excessive rainfall and wet fields. Necrotic ring blotch, a new suspected viral pathogen, was not prevalent, though red ringspot virus was observed. Powdery mildew and rust were also prevalent in some locations, though disease losses were not extensive. Exobasidium leaf and fruit spot were once again identified in one or two locations as well, and if this disease continues to be reported, it could become more of a production issue as opposed to a curiosity. Bacterial leaf scorch, a newly identified bacterial disease of southern highbush blueberries, continued to cause extensive losses on several varieties. Mummy berry was observed, but did not result in significant losses. Botryosphaeria canker was not prevalent in 2009, though it had resulted in significant losses in 2008; reduction in nitrogen fertilization and optimal timing of fertilizer applications likely resulted in less disease, since Botryosphaeria canker is correlated with high nitrogen fertility levels, which result in more succulent tissues for fungal invasion.

Disease % Reduction
in Crop Value
Damage
($ Thousands)
Cost of Control
($ Thousands)
Total
($ Thousands)
Mummy Berry 0.1 107.2 1,400.0 1,507.2
Botrytis Blight 1.0 1,071.8 560.0 1,631.8
Foliar Disease 1.0 1,071.8 420.0 1,491.8
Rots 2.0 2,143.6 140.0 2,283.6
Bacterial Scorch 0.1 107.2 10.0 117.2
Dieback 0.1 107.2 140.0 247.2
Phytophthora Root Rot 0.1 107.2 140.0 247.2
Total 4.4 4,716.0 2,810.0 7,526.0

Estimate by Phil Brannen, Extension Plant Pathologist

BUNCH GRAPE

Grape diseases were prevalent in 2009. Powdery and downy mildews were observed where spray programs were not well administered, and downy mildew resulted in a 100% loss at one location. In addition, crown gall was very prevalent in some new plantings, and this appears to have been related to transmission in transplants. 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 that is vectored by an insect, the glassy-winged sharpshooter. Cold winter temperatures either kill the insect that transmits the disease, or the temperatures may actually prevent the bacteria from surviving, but the verdict is still out as to 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 than ten vines per year to losses of several hundred vines, as observed in 2006 and 2007. Pierce?s disease losses were generally less extensive in 2009; colder winters in 2007/2008 and 2008/2009, combined with more aggressive insect management for Pierce?s disease vectors, likely resulted in reduced losses as compared to previous years. An initial survey of leaf roll virus diseases indicated that these are resulting in substantive losses in some vineyards, and the mealy bug vectors were also observed in these vineyards in 2009.

Disease % Reduction
in Crop Value
Damage
($ Thousands)
Cost of Control
($ Thousands)
Total
($ Thousands)
Botrytis 0.5 31.0 50.0 81.0
Downy Mildew 1.0 61.9 70.0 131.9
Black Rot 1.0 61.9 70.0 131.9
Powdery Mildew 3.0 185.7 20.0 205.7
Phomopsis Cane Blight 2.0 123.8 35.0 158.8
Crown Gall 0.5 31.0 5.0 36.0
Pierce’s Disease 0.5 31.0 30.0 61.0
Leaf Roll Virus 0.01 0.6 5.0 5.6
Total 8.5 526.9 285.0 811.9

Estimate by Phil Brannen, Extension Plant Pathologist

CORN

In 2009, corn for grain was harvested from 377,752 acres in Georgia with an average yield of 150.5 bu/A. The 2009 crop was valued at $203,266,035. Although southern rust (Puccinia polysora) was a significant problem for many corn growers in 2008, it did not appear until later in the 2009 field season and did not cause as much damage to the crop. Additionally, a second virulent race of P. polysora that was confirmed in Georgia in 2008 and that is able to overcome the resistance in hybrids with the rpp9 gene for southern rust was also present in 2009. Rainfall was abundant during much of the 2009 season and temperatures were generally cooler than in recent years. Cooler temperatures and a lack of tropical storms to aid in spore dispersal may in part explain the low severity of southern rust in 2009. Cooler and wetter weather may have also helped to reduce levels of aflatoxin in the harvested grain. Northern corn leaf blight (Exserohilum turcicum) was quite severe in many fields in 2009. In one field where northern corn leaf blight was particularly severe, yield was less than 100 bu/A despite an anticipated yield of 200+ bu/A. Use of fungicides, especially strobilurin chemistries, was common in 2009.

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 10.1 1.1* 11.2
Mycotoxins 2.0 4.1 0.0 4.1
Southern Corn Rust 1.0 2.0 1.7** 3.7
Northern Corn Leaf Blight 1.5 3.0 —** 3.0
Other Leaf Diseases trace 0.0 0.0
Total 9.6 19.4 2.8 22.2
* It is estimated that approximately 55,000 acres of corn were treated with 7 lb/A Counter insecticide-nematicide for control of nematodes.
** It is estimated that 110,000 acres of corn were sprayed with fungicides at least once during the 2009 season at a cost of $5/A for application and $10/A for cost of fungicide.

Estimate by Robert Kemerait, Extension Plant Pathologist

COTTON

It has been reported that cotton was harvested from an estimated 1,027,175 acres in 2009. The average lint yield was 956.6 lb/A. The crop was valued at $712,666,755.

Losses to seedling disease, primarily Rhizoctonia seedling blight, or "soreshin," were moderate in 2009. Stemphylium leaf spot, a significant problem in 2008, was less of a problem in 2009 due to increased rainfall and better transport of potassium to the foliage. A newly identified disease in Georgia, Corynespora leaf spot, was a significant problem in a number of fields in southwestern Georgia and resulted in premature defoliation where the disease was severe.

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. Abundant rainfall in 2009 did help to reduce the overall damage that could be attributed to nematodes.

Disease % Reduction
in Crop Value
Damage
($ Millions)
Cost of Control
($ Millions)
Total
($ Millions)
Boll Rot (lint) 1.5 10.7 0.0 10.7
Nematodes 7.0 49.9 10.6a 60.5
Southern Root-knot 5.0 35.6
Reniform 1.5 10.7 3.7
Columbia Lance 0.5 3.6
Seedling Disease 1.5 10.7 1.3b 12.0
Fusarium Wilt trace
Ascochyta Blight trace
Stemphylium Leaf Spot 1.0 1.7 0.3c 7.4
Corynespora Leaf Spot 2.0 14.2 14.0
Total 13.0 92.6 12.2 104.8
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% 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.
c This figure is based upon an estimate that 3% of the cotton acreage in the state was sprayed with a fungicide in 2009 to manage foliar diseases of cotton.

Estimate by Robert Kemerait, Extension Plant Pathologist

MUSCADINE GRAPE

Disease pressure was increased in most muscadine vineyards due to rainfall. Despite the increased moisture, good spray programs resulted in minimal losses. As a native grape, muscadines generally have less disease pressure than European grapes. Rot diseases result in more direct losses than any other disease category, but there are now multiple fungicides that adequately control these diseases. An active fungicide program is required, and diseases can be significant where producers are unable to spray effectively.

Status and Revision History
Published on Nov 8, 2010
Reviewed on Nov 30, 2013

Disease % Reduction
in Crop Value
Damage
($ Thousands)
Cost of Control
($ Thousands)
Total
($ Thousands)
Bitter Rot 1.0 59.4 50.0 109.4
Macrophoma Rot