Information Requests Monitoring System

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Request ID: 126
Request From: Steve Toth
Date Requested: May 20, 2005
Request: Note the following request from USDA's Office of Pest Management Policy for information of the use of Streptomycin and Oxytetracycline. Please forward this request to experts in your respective states/territories and send their responses to the Southern Region IPM Center Information Requests Monitoring System by Friday, June 3, 2005. Thanks. Steve Toth ----------------------------------- EPA is working on the preliminary risk assessment for streptomycin and oxytetracycline. They have asked us to gather some background information on the use of these chemicals. 1. How critical are the chemicals to growers? 2. What are the alternatives for these chemicals (in particular for fire blight)? 3. How do growers react to resistant pathogens (i.e., do they use an alternative, apply more product, or use other methods to manage pests)? Thank you in advance for all your help. Dhol Herzi Office of Pest Management Policy, USDA Telephone: (202) 720-2664 E-mail: dherzi@usda.gov

Responses
Responder: David Lockwood
State: TN
Date Requested: May 23, 2005
Response: 1. Streptomycin is an important chemical for apple growers in Tennessee and Georgia. Fireblight is an increasing problem for these growers since many of the new cultivars are fireblight sensitive (some, like Pink Lady, are extremely susceptible), and many of the dwarfing rootstocks are also quite susceptible. The economics of sustainable apple production dictate that growers use these new cultivars and rootstocks. Fireblight can be devastating to growers in Tennessee and Georgia. With severe infections, substantial tree loss has occurred. Even with less severe infections, fireblight can increase the cost of producing a crop of apples due to the need for additional sprays, increased pruning costs and loss of fruit wood in trees. 2. While there are other practices and chemicals that may provide some help in prevention of fireblight, I am not aware of any additional chemicals for use in fireblight control during bloom. 3. Growers are aware of the potential for streptomycin resistance in fireblight. In fact a few instances have been reported in the Southeast. They are also aware that even under the best of conditions, streptomycin will help reduce the intensity and frequency of fireblight infections but will certainly not prevent all infections. Therefore, they are encouraged to adopt a comprehensive management program that will lessen the potential for fireblight. These practices begin with orchard site selection and development. Postplant practices include the use of copper fungicides immediately previous to bloom, reduced nitrogen use to lessen tree vigor, the possibility of using Apogee to lessen the period of shoot elongation thus reducing the duration of time in which the shoot blight phase of fireblight is a threat, controlling mites and insects such as aphids that may cause increased fireblight problems during the growing season, and a judicious pruning program to remove infected sites. Some pruning for this prupose is conducted during the growing season as fireblight strikes appear, however, the benefits of this practice are under question. Dormant pruning to remove cankers is always practiced. Most growers are quite conscientious in using a multi-pronged attack on fireblight. Where possible, growers select cultivars and rootstocks that show less susceptibility to fireblight than other cultivars. However, this approach is not always possilbe as the market demand for new cultivars that are fireblight susceptible and the economic benefits of using full-dwarfing rootstocks leave the growers no other options than to plant fireblight susceptible cultivars and rootstocks. 1. Oxytetracycline is used in Tennessee to lessen losses due to bacterial leaf spot in stone fruits, which can be serious in some years causing substantial leaf loss which impacts fruit size and tree health. Bacterial spot can also cause loss of fruit due to damage on the fruit. Oxytetracycline is important to stone fruit growers in Tennessee as damage due to bacterial spot can be extensive in some years and with some cultivars. 2. Copper fungicides applied just prior to bloom may have some benefit in controlling bacterial spot. Applications of copper during the growing season may likewise help to control infection, however, damage to foliage and fruits at this time is a threat. 3. Where possible, growers are selecting cultivars showing resistance to bacterial spot. However, considering the need to have a constant supply of ripe fruit throughout the growing season to hold on to markets, there are not enough resistant cultivars. In addition, in some years, substantial problems with bacterial spot can occur with resistant cultivars. The threat from bacterial spot and the less than absolute control achieved from the use of oxytetracycline, plus the substantial cost involved, has been a major factor in the use of other management practices for control of this disease.

Responder: Bob Bellinger
State: SC
Date Requested: May 23, 2005
Response: Request:
EPA is working on the preliminary risk assessment for streptomycin and oxytetracycline. They have asked us to gather some background info ...
1. How critical are the chemicals to growers?
Streptomycin is critical for apple growers for fire blight control. Oxytetracycline is critical for peach growers for bacterial spot control. Elimination of these disease management options would threaten the production of pome and stone fruits in SC.
2. What are the alternatives for these chemicals (in particular for fire blight)?
There is no other options with efficacies comparable to streptomycin for fire blight control on apples. For peaches, copper based products are effective early in the season. They cannot be applied at high rates during the growing season, however, because copper is phytotoxic to actively growing plant tissue. In other words, we do not have management options for bacterial spot other than oxytetracycline during the growing season.
3. How do growers react to resistant pathogens (i.e., do they use an alternative, apply more product, or use other methods to manage pests)?
So far no resistance to streptomycin or oxytetracycline has been reported in SC.
end

Responder: Phillip Brannen
State: GA
Date Requested: May 28, 2005
Response: 1. How critical are the chemicals to growers? IN BOTH CASES, THESE ANTIBIOTICS ARE CURRENTLY NECESSARY FOR CONTINUED PRODUCTION OF THE COMMODITIES IN QUESTION. STREPTOMYCIN IS THE ONLY EFFECTIVE CONTROL OF THE BLOSSOM BLIGHT PHASE OF FIRE BLIGHT, AND ITS USE IS CRITICAL FOR MANY APPLE CULTIVARS AND ROOTSTOCKS, AS WELL AS ASIAN PEARS AND MAYHAWS IN GEORGIA. OXYTETRACYCLINE WOULD BE THE ONLY ACCEPTABLE ALTERNATIVE TO STREPTOMYCIN IF RESISTANCE WERE OBSERVED IN GEORGIA, AND OXYTETRACYCLINE IS GENERALLY NOT AS EFFECTIVE AS STREPTOMYCIN IN NONRESISTANT SITUATIONS. THOUGH THERE ARE OTHER PRODUCTS REGISTERED FOR FIRE BLIGHT CONTROL, NONE OF THESE PROVIDE SUBSTANTIVE CONTROL UNDER OUR ENVIRONMENTAL CONDITIONS. OXYTETRACYCLINE IS EQUALLY CRITICAL FOR COVER SPRAY CONTROL OF BACTERIAL SPOT OF PEACH. IT IS THE ONLY REGISTERED MATERIAL WHICH CAN LEGALLY BE UTILIZED THROUGHOUT THE COVER SPRAYS. COPPERS ARE LIMITED BY LABEL TO EARLY COVER SPRAYS, AND THEY ARE GENERALLY LIMITED TO VERY FEW SPRAYS, BOTH BY LABEL AND BY PHYTOTOXICITY ISSUES. 2. What are the alternatives for these chemicals (in particular for fire blight)? CURRENT ALTERNATIVES FOR FIRE BLIGHT (BLOSSOM BLIGHT) INCLUDE BIOLOGICAL CONTROLS (BLIGHT BAN OR SIMILAR BACTERIAL MATERIALS SUCH AS SERENADE), OR INDUCED SYSTEMIC RESISTANCE CHEMICALS SUCH AS PROPHYT OR ALIETTE -- NONE OF WHICH GIVE SUBSTANTIAL CONTROL IN OUR ENVIRONMENT (WARM AND WET DURING BLOOM). ALTERNATIVES FOR OXYTETRACYCLINE ARE CURRENTLY LIMITED TO LOW RATES OF COPPER, WHICH ARE ONCE AGAIN LARGELY RESTRICTED BY LABEL AND PHYTOTOX ISSUES. 3. How do growers react to resistant pathogens (i.e., do they use an alternative, apply more product, or use other methods to manage pests)? IF OTHER PRODUCTS ARE AVAILABLE, GROWERS WILL GENERALLY SWITCH TO THE ALTERNATIVE PRODUCT. IT IS GENERALLY NOT LEGAL TO INCREASE THE RATE OF A PRODUCT, SO THIS IS NOT USUALLY AN OPTION. GROWERS UTILIZE BEST-MANAGEMENT PRACTICES WHICH WOULD HELP TO CONTROL FIRE BLIGHT OR BACTERIAL SPOT, SO THE ADVENT OF RESISTANCE WILL NOT SUBSTANTIALLY CHANGE METHODS UTILIZED TO MANAGE THESE DISEASES OF EITHER APPLE OR PEACH.

Responder: Kenneth Seebold
State: KY
Date Requested: Jun 02, 2005
Response: See attached file
Attachment included in response [Download]

Responder: Charles Luper
State: OK
Date Requested: Jun 03, 2005
Response: According to our Plant Pathologist Streptomycin and Oxytetacycline are very important since they are the only bacteriacides we still have availabe other than copper. Dr. John Damicone's response is below. I can only speak to veg crops. Streptomycin is an important tool for managing bacterial diseases (bacterial spot and speck) in tomato and pepper transplant production, and for managing seed borne bacterial disease on bean (seed treatment). Alternatives are lacking. Copper can be used in transplant production. No alternatives for snap beans. We need to keep these because alternatives for bacterial disease control in general are very limited. Resistance is a problem for all bactericides (including copper). Best managed by alternating copper w/ strptomycin.

Responder: Tom Melton
State: NC
Date Requested: Jun 03, 2005
Response: 1. How critical are the chemicals to growers? Extremely critical for tobacco farmers who get foliar bacterial diseases or bacterial diseases in seedling production. Those diseases may not be a problem for several years and then can be devistating locally in wet years. 2. What are the alternatives for these chemicals (in particular for fire blight)? None in tobacco 3. How do growers react to resistant pathogens (i.e., do they use an alternative, apply more product, or use other methods to manage pests)? Resistance not recognized in tobacco, the product is only used when there is a need, not preventive. Thomas A. Melton Associate State Program Leader, AgNR/CRD North Carolina State University Cooperative Extension Service

Responder: David Ritchie
State: NC
Date Requested: Jun 03, 2005
Response: 1. How critical are the chemicals to growers? FOR PEACH GROWERS CURRENTLY THERE IS NO SATISFACTORY ALTERNATIVE TO OXYTETRACYLINE FOR POST FRUIT-SET USE AGAINST BACTERIAL SPOT (XANTHOMONAS ARBORICOLA PV. PRUNI). LOW RATES OF COPPERS ARE USED BUT THERE REMAINS THE RISK OF UNACCEPETABLE PHYTOTOXICITY RESULTING IN DEFOLIATION. STREPTOMYCIN IS NOT AN ISSUE FOR PEACHES. THE BACTERIAL SPOT PATHOGEN RAPIDLY DEVELOPS RESISTANCE AND IS NOT LABELED ON PEACHES. 2. What are the alternatives for these chemicals (in particular for fire blight)? FOR PEACHES NO COMPLETELY ACCEPTIBLE ALTERNATIVES. SEE COMMENT ABOVE ABOUT COPPER. SERENADE AND PHOSPHITE MATERIALS ARE BEING TESTED. ACTIGARD WAS NOT HELPFUL ON HIGHLY SUSCEPTIBLE CULTIVARS. 3. How do growers react to resistant pathogens (i.e., do they use an alternative, apply more product, or use other methods to manage pests)? RESISTANCE TO OXYTETRACYCLINE HAS NOT BEEN DETECTED. GROWERS USE COPPER EARLY IN THE SEASON (PRE-FRUIT SET) AND THEN LOW RATES (~ 1 OZ ELEEMENTAL COPPER/A) TANK-MIXED OR ALTERNATED WITH OXYTETRACYCLINE. HOST RESISTANCE IS PRESENT BUT NOT IN MOST OF THE HIGHLY IMPORTANT CULTIVARS MOST OF WHICH HAVE BEEN DEVELOPED FOR WEST COAST MARKETS. LOSS OF OXYTETRACYCLINE FOR USE ON PEACHES AGAINST BACTERIAL SPOT WOULD BE ECONOMICALLY DEVESTATING FOR HIGH QUALITY PEACH PRODUCTION IN THE EASTERN AND ESPECIALLY SOUTHEASTERN U.S. Dave Ritchie Department of Plant Pathology North Carolina State University

Responder: Turner Sutton
State: NC
Date Requested: Jun 03, 2005
Response: 1. How critical are the chemicals to growers? For apple growers streptomycin is the only product that provides consistent control of fire blight. Oxytetracycline is not registed on apples in North Carolina (though I think it has a Section 18 registration in some states where the fire blight bacterium is resistant to streptomycin). 2. What are the alternatives for these chemicals (in particular for fire blight)? There are some bioloical controls registered, but their perforrmance isn't consistent. The growth regulator Apogee reduces the amount of damage (by limiting/hardining off growth), but its not really a control. Cu products are too phytotoxic. 3. How do growers react to resistant pathogens (i.e., do they use an alternative, apply more product, or use other methods to manage pests)? As far as I know (I haven't looked very hard) we don't have a resistance problem in North Carolina. Dormant Cu sprays are used to reduce the overwintering inoculum. Some growers will mix streptomycin and one of the biocontrol agents to help avoid reistance.

Responder: Phillip Brannen
State: GA
Date Requested: Jun 03, 2005
Response: 1. How critical are the chemicals to growers? IN BOTH CASES, THESE ANTIBIOTICS ARE CURRENTLY NECESSARY FOR CONTINUED PRODUCTION OF THE COMMODITIES IN QUESTION. STREPTOMYCIN IS THE ONLY EFFECTIVE CONTROL OF THE BLOSSOM BLIGHT PHASE OF FIRE BLIGHT, AND ITS USE IS CRITICAL FOR MANY APPLE CULTIVARS AND ROOTSTOCKS, AS WELL AS ASIAN PEARS AND MAYHAWS IN GEORGIA. OXYTETRACYCLINE WOULD BE THE ONLY ACCEPTABLE ALTERNATIVE TO STREPTOMYCIN IF RESISTANCE WERE OBSERVED IN GEORGIA, AND OXYTETRACYCLINE IS GENERALLY NOT AS EFFECTIVE AS STREPTOMYCIN IN NONRESISTANT SITUATIONS. THOUGH THERE ARE OTHER PRODUCTS REGISTERED FOR FIRE BLIGHT CONTROL, NONE OF THESE PROVIDE SUBSTANTIVE CONTROL UNDER OUR ENVIRONMENTAL CONDITIONS. OXYTETRACYCLINE IS EQUALLY CRITICAL FOR COVER SPRAY CONTROL OF BACTERIAL SPOT OF PEACH. IT IS THE ONLY REGISTERED MATERIAL WHICH CAN LEGALLY BE UTILIZED THROUGHOUT THE COVER SPRAYS. COPPERS ARE LIMITED BY LABEL TO EARLY COVER SPRAYS, AND THEY ARE GENERALLY LIMITED TO VERY FEW SPRAYS, BOTH BY LABEL AND BY PHYTOTOXICITY ISSUES. 2. What are the alternatives for these chemicals (in particular for fire blight)? CURRENT ALTERNATIVES FOR FIRE BLIGHT (BLOSSOM BLIGHT) INCLUDE BIOLOGICAL CONTROLS (BLIGHT BAN OR SIMILAR BACTERIAL MATERIALS SUCH AS SERENADE), OR INDUCED SYSTEMIC RESISTANCE CHEMICALS SUCH AS PROPHYT OR ALIETTE -- NONE OF WHICH GIVE SUBSTANTIAL CONTROL IN OUR ENVIRONMENT (WARM AND WET DURING BLOOM). ALTERNATIVES FOR OXYTETRACYCLINE ARE CURRENTLY LIMITED TO LOW RATES OF COPPER, WHICH ARE ONCE AGAIN LARGELY RESTRICTED BY LABEL AND PHYTOTOX ISSUES. 3. How do growers react to resistant pathogens (i.e., do they use an alternative, apply more product, or use other methods to manage pests)? IF OTHER PRODUCTS ARE AVAILABLE, GROWERS WILL GENERALLY SWITCH TO THE ALTERNATIVE PRODUCT. IT IS GENERALLY NOT LEGAL TO INCREASE THE RATE OF A PRODUCT, SO THIS IS NOT USUALLY AN OPTION. GROWERS UTILIZE BEST-MANAGEMENT PRACTICES WHICH WOULD HELP TO CONTROL FIRE BLIGHT OR BACTERIAL SPOT, SO THE ADVENT OF RESISTANCE WILL NOT SUBSTANTIALLY CHANGE METHODS UTILIZED TO MANAGE THESE DISEASES OF EITHER APPLE OR PEACH. Phillip M. Brannen 2106 Miller Plant Sciences Building Athens, GA 30602 (W) 706-542-1250 (M) 706-207-3805

Responder: Kelly Ivors
State: NC
Date Requested: Jun 03, 2005
Response: 1. How critical are the chemicals to growers? Streptomycin sulfate (Agri-mycin 17) is very critical for tomato transplant production in North Carolina. It is the only active ingredient labeled and effective for controlling bacteria (bacterial speck, spot, and canker) in the greenhouse. If used on a preventative basis, it helps growers produce bacteria-free transplants. Once tranplants have bacteria, they introduce it into the fields where severe damage can occur. Hence, it is very important to have available for growers to use. 2. What are the alternatives for these chemicals (in particular for fire blight)? There are no alternatives in the greenhouse for tomatoes, although once in the field there are 2 alternative chemicals....acidbenzolar-S-methyl (actigard) or copper. However, some populations of bacteria are copper insensitive so if resistant populations exist, then the only alterative is actigard. Actigard can only be applied up to 4 times in the field however. 3. How do growers react to resistant pathogens (i.e., do they use an alternative, apply more product, or use other methods to manage pests)? Tomato growers in North Carolina will usually apply alternative chemicals because they exist. Usually they only apply alternatives when they are cheaper in cost however.

Responder: Mark Mossler
State: FL
Date Requested: Jun 03, 2005
Response: With regard to streptomycin use in FL - it is not used in food related agriculture. It is used by growers of certain tropical ornamental plants. It is applied by growers who wish to manage soft-rot bacteria such as Erwinia. In talking to the extension specialist about this, it is apparent that although the growers may think they need this antibiotic, these bacteria have been resistant to it for some time. So although the growers may think they are losing a valuble tool - this may not be the case. Growers use sanitation and clean propagule production, in addition to coppers and phosphonics to manage Erwinia. For those who steadfastly use streptomycin, they have it in a standard two-week rotation. With regard to oxytetracycline use in FL - it is only used as an injectable material on coconut palms to control palm lethal yellows (a phloem phytoplasma). This is the only material available for this disease and it is only registered to one group. At one point, coconut palms that were resistant were thought to exist, but that has been proven false. However, this organism has yet to show resistance to oxytetracycline. The recommendations are also not to eat the coconuts from treated trees (coconut palm used almost exclusively as ornamental in FL). So this appears to be a contained and critical use for oxytetracycline.

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