Pesticide Use and IPM

I think many of you will find this statement interesting and very applicable for both conventional and organic producers of all crops.


Statement on “Least Toxic” & “Last Resort”

Recommendations and decisions to use “least toxic pesticides” and “pesticides as a last resort” have flourished in the last decade, but according to three scientific organizations – the Weed Science Society of America (WSSA), the American Phytopathological Society (APS) and the Plant-Insect Ecosystems Section of the Entomological Society of America (P-IE ESA) – these are not the correct approaches to the pesticide component of an Integrated Pest Management (IPM) program. The three organizations have joined to take an objective look at these two descriptions and prepared a position statement.

It is essential to practice integrated pest management (IPM), whether managing weeds, insect pests or plant disease - on the farm, on commercial sites, on public lands, or in or around the home. Key components of IPM include making the habitat unfavorable for pests, excluding pests where feasible, using proper sanitation practices, monitoring the infestation level, knowing the pest tolerance level for the specific situation and implementing the necessary management practices. Judicious use of pesticides is a critical component of many IPM programs.

Judicious (careful) use refers to various practices - following all label directions and making all appropriate stewardship decisions required in the particular situation. This includes applying a product registered for the target pest(s) after accurate pest identification, and consideration of the level of infestation and the potential for economic, health or other negative pest impacts. Careful use extends beyond pesticides to household chemicals, automobiles, medicines, alcoholic beverages, and countless other products that are part of our daily lives.

“Least toxic” implies there are pesticides available for every pest spectrum that are least toxic to everything else. This is not true. The toxicity of a pesticide depends on what is being evaluated and who or what may be affected. It is also important to remember that toxicity is not the same as risk, which is dependent on both toxicity and exposure. The risk associated with the use of pesticides and other chemicals is managed by establishing safe exposure levels based on the toxicity specific to each product. Assigning a “most” or “least” toxic rating does not equate to actual risk when the product is properly applied.

“Last resort” implies that pesticides will work as well when every non-chemical control technique is attempted first. However, delaying application of a pesticide can cause buildup of the pest(s) in crops, gardens, buildings and other sites, with negative impacts on yield, quality and/or health. In fact, delaying treatment can significantly increase the ecological and economic damage to crop and non-crop areas.

Using pesticides as the last line of defense can result in a more limited choice of pesticides, as well as reduced crop tolerance, the need for higher rates, and less effective control because of higher infestation levels and/or more tolerant pest stages. For example, seedling weeds and early-stage insect larvae and diseases are usually more easily controlled than later pest stages. Effective pesticide choices, when they are applied as a “last resort,” means fewer options to rotate pesticides, which is a critical step in preventing a pest from becoming resistant to a pesticide. “Last resort” pesticide strategies may also increase the need for multiple products and higher application rates to control the pest effectively. The term also suggests pesticides are always the worst choice, which is not true. First using non-chemical techniques that are ineffective or inefficient has the potential to add to the cost of pest management, intensify the pest problem or create new problems.

Finally, by branding pesticides as the “last resort” choice certainly does not stimulate a strong public interest in funding education on their proper use. Pesticides are widely used, but discretionary federal funding of the U.S. Pesticide Safety Education Program has been eliminated in 2011 and 2012.

This program is vital to educate pesticide users and dealers who must be certified to apply or sell pesticides, and to teach the public how to use pesticides safely. There is no benefit or scientific basis to simplistic messages like “use least toxic pesticides as a last resort” for the large number of pesticide users who apply pesticides according to the label and practice good stewardship. Nor are these messages beneficial for those who neither seek training nor adequately read the label believing instead that it is safe, practical, and effective to simply choose a product considered a “least toxic pesticide” and apply it only as a “last resort.” These messages hinder pesticide safety and stewardship education and practices that are in the best interest of the pesticide user, our food supply, public health and ecosystem preservation.

(WSSA/APS/P-IE ESA joint statement, 11/12/12).

Cucurbit Downy Mildew in Western NC

Cucurbit downy mildew has been identified on cucumbers in Buncombe and Haywood Counties.  Growers are urged to scout their fields and begin preventive management.

Review control measures and previous posts on this major disease issue - Cucurbit downy mildew

Water soaked lesions, caused by Pseudoperonospora cubensis (causal agent of cucurbit downy mildew), visible on the underside of cucumber leaf.

Also, please visit the Cucurbit Downy Mildew Forecasting site to see more pictures of the disease, review control measures, report disease outbreaks in your area and more.

Late Blight Identified in Western NC

Late blight has been positively identified in Henderson County.  Please review the NC Alternative Crops and Organics for a synopsis from Dr. Jeanine Davis and control recommendations and descriptions of the disease from Dr. Kelly Ivors - Late Blight Confirmed in Western NC.

Growers are urged to start scouting fields and taking proper preventive measures- it is very hard to play catch up with late blight, prevention is key.

To review previous posts on late blight, click here.

Pennsylvania Potato and Tomato Growers Hit By Late Blight

Penn State Live is reporting the current outbreak of late blight on potato and tomato.  Late blight has not been found in Western NC, but growers should be scouting their fields.

For more information or to see pictures of the disease, review the post from June 3

Read the article: http://live.psu.edu/story/60029

Pest News June 1, 2012

Though this week's NC Pest News does not contain anything specifically about vegetable or fruit pests (though kudzu bugs may be a problem for folks growing edamame), I did want to draw your attention to some possible issues to be on the lookout for.

Cucurbit downy mildew and late blight of potato and tomato are very devastating and rapid moving diseases.  Though we do not have any reports of these diseases in WNC or our immediate surrounding areas, they have been reported in other parts of NC.  Weather has been ideal for both of these diseases in our area, cool and wet.  Also, because weather has been unsettled (many storms moving throughout the east coast) there is a chance that the spores of these pathogens could travel to WNC.

In fact, the Cucurbit Downy Mildew Forecasting site issued WNC a low risk warning on Friday.  Cucurbit downy mildew has both been detected in eastern and central NC.  On June 1, new reports of the disease were confirmed as close as Franklin, Nash and Wake Counties in NC.  Cucurbit downy mildew is also tracking up the east coast into New Jersey.  To view a map of current Cucurbit Downy Mildew outbreaks visit the CDM IPM Pipe website.  Growers are advised to scout for this disease and to report to their local cooperative extension office if they need assistance or to report an outbreak. 

 

Symptoms of cucurbit downy mildew on cucumber are angular lesions that start a pale green and progress to bright yellow and then finally brown (above).  The best way to identify cucurbit downy mildew is to turn the leaf over to look for the downy growth of the pathogen's spores (below). 

 

Late blight on potatoes has also been detected in Camden County, NC and various other states on the east coast.  To view a current map of these outbreaks, visit the USABlight website.  Growers are urged to scout for this disease as well, as we know this can be a deal breaker for organic producers especially.

 

Late blight on a tomato leaf.

  Again, these diseases have not been reported in WNC.  If you suspect you have these diseases in your planting, please contact your local Cooperative Extension office for assistance.  It is reporting and early detection that can save a planting!

Cucurbit Downy Mildew and Powdery Mildew Early

There have been unusually early reports of both downy mildew (Pseudoperonspora cubensis) and powdery mildew (Podosphaera xanthii and Erysiphe cichoracearum) on cucurbits in the southeast this season.


Growers are encouraged to be on the lookout for these diseases and to call their local cooperative extension office if they need identification help, management recommendations and to report disease.

DOWNY MILDEW
Southeast Farm Press. May 11. 2012: Downy mildew showing up early in cucumbers.

Cucurbit Downy Mildew Found in NC, Rapid Response and Implications for Local Growers.

Frank J. Louws (1), Wendy Britton (1), Peter Ojiambo (1) and Billy Little (2). (1) Department of Plant Pathology, NCSU; (2) Cooperative Extension, Wilson NC.

There was a confirmed report of cucurbit downy mildew (CDM) in a hoop house in Wilson County, NC on May 3, 2012.  The house contained 2 rows of trellised cucumbers and about 20 vines had early symptoms.  The infection was about 5% and with actively sporulating lesions.

Wilson Cooperative Extension, the NCDA, NCSU specialists, and the CDM ipmPIPE team actively worked to contain this outbreak as soon as possible. Discussions with the grower, industry representatives, and state/University employees reached a quick consensus that the best course of action was to destroy all cucumber vines. The vines were cut, roots extracted, all debris swept up and placed in plastic bags. The contained plant material was carried from the greenhouse and buried at the edge of a field that will not be cultivated this season. This was completed and verified as of 2:00 pm Friday May 4, 2012.

CES and industry knowledge about the area suggested field cucumbers were not present in the vicinity and the inoculum from the hoop house presented a zero to low risk to the industry as a whole. The CDM ipmPIPE subsequently changed the status of this outbreak from "confirmed" to "no longer found".  The county in NC will remain on the map but will not be forecasted as an active source. This data is available at http://cdm.ipmpipe.org.

The only other recorded incidence of CDM is in south Florida. Based on recent weather patterns, there is no evidence the inoculum originated from south Florida and there are no field reports of CDM north of south Florida. A thorough examination suggested the grower used optimum best management practices regarding sanitation, removal of all volunteers and other standard practices. Thus, the source of inoculum remains unknown. However, early detection, rapid destruction and historical weather patterns provide high confidence the problem was contained and does not represent a threat to the industry. At this time, we would not recommend implementation of spray programs to manage CDM in cucumber fields in NC. Monitoring of local fields and forecasting spore dispersal from known sources in south Florida will continue and observations will be posted at the CDM ipmPIPE website.

For further information or questions do not hesitate to call Dr. Frank Louws 919-515-6689 or email frank_louws@ncsu.edu (use subject line Downy Mildew).  

To view previous posts on cucurbit downy mildew click here


POWDERY MILDEW
Dr. Tony Keinath, Clemson University Extension Plant Pathologist, sent out a Timely Talk Update about the presence of powdery mildew on watermelons already this season.  To learn more go to Early Outbreak of Powdery Mildew on Watermelon in South Carolina.

To learn more about cucurbit powdery mildew click here.

Pest News April 27, 2012

The latest edition of NC Pest News in now available.

In this edition you will find the following articles related to Fruits and Vegetables:

1. What causes misshapen strawberries?
2. Be on the look-out!  Garden diseases to watch for in May and June.

New Rust Found on Eggplant in Florida

It seems like this year will be challenging for pest control on vegetables. Please see the message below from Gene McAvoy, County Extension Director in Hendry County, FL.

Dr Pam Roberts reports a new find of rust on eggplant in SW Florida.

Rust detected on eggplant (Solanum melongena) in Southwest Florida Pamela D. Roberts, Katherine Hendricks, and Mark Verbeck 3/3/2012

Lesions were detected on the top of eggplant leaves that were roughly circular, with a yellow halo and a dark center. Lesions on the undersides of the leaves were similar except they were a bit smaller and contained pustule, cup-like structure with erupting yellow to orange spores.

Microscopic examination revealed that the individual structures (aecia) contained spores (aeciospores). Spores were red-orange in color and round to ovoid.

A rust disease caused by Puccinia sp. was described on eggplant in Georgia in 1997. Eggplant was the aecial host for the rust pathogen of pearl millet (Pennisetum glaucum). We suspect this is the same rust and will follow with additional testing.

In this outbreak, nearly every eggplant in a 10 acre field was affected. Plants are mature and have been harvested 2 to 3 times. No symptoms occurred on fruit.

To see pictures of the disease and read more about, please visit Eggplant Rust Alert.

Grafting for Disease Resistance and Increased Productivity

Researchers around the world have demonstrated that grafting can protect plants against a variety of soil-borne diseases in various climates and conditions. Grafting has been successfully implemented in many countries to battle diseases such as Verticillium and Fusarium wilt, corky root rot and bacterial wilt, among others. Along with maintaining high fruit quality, tomato grafting can also help overcome abiotic stressors, such as high salinity, excess moisture and soil temperature extremes, even allowing the extension of the growing season.


SARE has a new fact sheet, Tomato Grafting for Disease Resistance and Increased Productivity, that helps farmers and agricultural educators learn how to graft tomatoes to fight disease and improve the health and vigor of tomato crops.


Growers interested in experimenting with this novel approach of improving resistance to soil-borne pathogens will find:


• Helpful tips for grafting plants, including variety selection based on
resistance to particular diseases, step-by-step grafting techniques and caring
for grafted plants;

• Instructions for building a healing chamber for newly grafted plants, and for
transplanting them to the field;

• An analysis of the economic viability of grafting under different conditions.


Still a relatively uncommon practice in the United States, researchers around
the world have demonstrated that grafting can protect plants against a variety of soil-borne fungal, bacterial, viral and nematode diseases, such as Verticillium and Fusarium wilt (FW), corky root rot, root-knot nematodes, bacterial wilt, southern blight and other diseases.


Grafting is on the rise in the United States, since it has been shown to successfully manage bacterial wilt in tomatoes, even in severely infested soils.


In western North Carolina, for example, a resistant rootstock was used to reduce bacterial wilt in tomatoes: At season's end, nearly 90 percent of the control plants died while 100 percent of the grafted plants not only survived, but their yield was more than two fold that of the surviving non-grafted plants.


Want more information? See the related SARE grant(s) GS05-046, Inducing Disease Resistance and Increased Production in Organic Heirloom Tomato Production Through Grafting, GS07-060, Potential of grafting to improve nutrient management of heirloom tomatoes on organic farms, LS06-193, Grafting Rootstocks onto Heirloom and Locally Adapted Tomato Selections to Confer Resistance to Root-knot Nematodes and other Soil Borne Diseases and to Increase Nutrient Uptake Efficiency in an Intensive Farming System for Market Gardeners, and OS09-046, Grafting Heirloom Tomatoes on Disease Resistant Rootstock in Western North Carolina.

Go to SARE's Learning Center for these and other publications.
http://bit.ly/uoHJOT

Attention Strawberry Growers: Phytophthora cactorum

By Dr. Frank Louws, NCSU Dept. of Plant Pathology with contributions by Dr. Barclay Poling, Professor Emeritus, NCSU Dept. of Horticultural Science; Dr. Chuck Johnson, Virginia Tech, SPAREC; Dr. Powell Smith, Clemson Extension, Lexington Co.; and David Dycus, NCDA Regional Agronomist

Berry Alert No. 99

September 9, 2011 (Friday)

Subject: Frequently Asked Questions about Managing Phytophthora cactorum (Pc) in strawberry tips and plugs

Introduction:

Since the Labor Day weekend, a NC nursery plant supplier with runner tips grown on PEI, Canada, has been in touch with their customers to inform them of a problem with Phytophthora cactorum (Pc), which is the causative agent of Phytophthora root and crown rot.

Growers who have received such a call from their plant supplier are understandably concerned, and in many instances, they have in turn called their local extension agent, NCDA field agronomist, or various specialists here in the Mid-south at NC State, Clemson and Va Tech. This is not a new problem for our industry, and quite frankly this particular disease does lend itself to some "cures". As Dr. Powell Smith wrote to a South Carolina grower on Wednesday this week:

"If you have suspicious-looking tips (necrotic [decayed] looking), you can send those to the Clemson Plant Problem Clinic. They will be able to find the Pc on the tips if it is there. Also, any plants looking to be suffering from root rot in the plug house, send those immediately to the PPC for diagnosis. Time is of the essence; there are cures."

Indeed, there are some "cures", and this where I think many growers need realize that this is a situation that can be reasonably well managed, and one important step is to get a "proper diagnosis" if you are seeing some suspicious-looking tips. If you are having any question on where to go with strawberry tips/plugs for diagnosis, let us know!

In North Carolina, we have the Plant Disease and Insect, and here is the website to get directions for submitting a plant sample:

http://www.cals.ncsu.edu/plantpath/extension/clinic/submit-sample.html

Here is the form for Clemson: http://www.clemson.edu/agsrvlb/plant-prob-diag-form.PDF

Phytophthora problems in plug plants. Notice the distinct black lesions. Botrytis will be brown and usually have gray fuzz. Also, note the poor root formation resulting in plant collapse as the misting frequency decreases.

(photo courtesy of Dr. Frank Louws)

In the interest of time today, we review below questions we have received in the last day or two about this situation:

Question 1. We have received some tips from the nursery that has reported having some Pc on the tips/plugs, and we are seeing plugs at our location that are doing fine, and rooting well after 8 days. We have no idea how we could dip 60,000 tips now that they have been set and we were told that Aliette was our best option. We need your advice!

Answer 1. First: Aliette is a fungicide product that is in the phosphorous acid family of fungicides. Since Aliette is off-patent, multiple other products have been registered and include Prophyt, Phostrol and others. These are commonly referred to as phosphonate or phosphite fungicides and do not provide any nutrient benefit to the plant. These products are not to be confused with products in the phosphoric acid family commonly used as a source of nutrients to the plant (e.g. Nutri-Phite and similar products). The label for the phosphite fungicides is written with perennial or field production systems in mind and therefore it is very difficult to directly interpret the label for this type of need. “Preplant dips” are allowed and applications within 14 days”after planting” are allowed. Thus, timing in plug facilitates is unclear but the label does not prohibit use of treating transplant trays or other “nursery” type setting.

Second, it is encouraging that you are not seeing suspicious-looking tips (necrotic [decayed] looking)! The moment symptoms appear, it would be productive to send samples to the local clinic for diagnosis asap. You are quite correct in questioning how you might go about dipping 60,000 tips, as you are already past that point! If you were just now receiving an order of tips for plugging, then perhaps a dip of a phosphite fungicide would be in order. In your case, the plugs have now been growing 8 days, and it turns out that phosphite fungicide treatment even at 4-7 days should be helpful, and a second treatment may be appropriate 4 to 7 days before going to the field (usually plugs root for a full 4 weeks, and for the first full week they are typically under some type of misting schedule in the day, and by about 7-8 days, the plugs have established enough of a root system so that much less misting is required). In one experiment done at NCSU, dipping the tips prior to plugging, spraying the plants soon after setting, and early dip/sprays followed by a second foliar application 14 days later all gave similar results for controlling Phytophthora problems in plug plants. Prophyt and Aliette gave similar results. As far as the actual "treatment", you would need to spray your 8 day old plugs with Aliette at the rate of 2.5 lbs/100 gallons/acre, 2 pints/100 gal (ProPhyt), or 2.5 pints/100 gal (Phostrol). Now, if you have 60,000 plugs, your plugs are covering about 2600 sq ft, or only 0.06 acre (2600/43560). Thus, using Aliette as an example, the amount of product needed to spray this much area would only be 0.15 lb, or 2.4 oz. Foliar spray volumes to deliver this phosphite product work best with sprays applied just prior to runoff, but if we were to stick with 100 gallons/acre, then for an area of 2600 sq ft you would need to apply 6 gallons of water. The key concept is that the phosphites are absorbed by foliage and roots, not just by roots as with Ridomil, and the phosphite product should be in sufficient water to promote as much uptake as possible by the leaves and other plant parts without creating drenched conditions in the potting medium or promoting splash dispersal among plugs on the pad. Aliette is known to cause damage in other crops if excess amounts go into the soil and if other products may be present (e.g. certain insecticides, copper, surfactants etc).

Question 2. Since the phosphite fungicides can be applied as a foliar spray my next question has to do with how much of a "drying period" is needed after you have sprayed the plugs? (of course, if the plugs are still under mist during the first week, then the only dry period is the evening)

Answer 2. The phosphites are unique chemicals in that they are absorbed by the roots and the foliage and they become systemic in the plant, moving up and down. They are absorbed fairly readily into the plant and as a rule of thumb for systemic fungicides, they probably require about 90 minutes of drying time for the majority of the product to be taken systemically into the plant. The fungicide has direct as well as indirect (changing the biochemistry of the plant) activity against the pathogen offering curative control (it can stop the pathogen from growing more inside the strawberry tissue). Therefore, if plants are under a mist schedule, the best time to apply the fungicide is towards the end of the day when the misting cycles are off. This allows maximum absorption into the plant and limits excess runoff into the soil. Avoid excess saturation of the growing media. Phytophthora is a water mold and the more free water there is the more the pathogen can spread.

Question 3. Once my plugs are out from under the mist in the 2nd week and thereafter, can you advise on whether a follow-up treatment with Aliette may be needed?

Answer 3. As mentioned above, a second treatment did not seem to offer an advantage. The product is systemic in the plant and seems to persist for long periods of time. However, if a second application is made, it is probably best done 4-7 days prior to planting to allow the fungicide to be absorbed into the plant but to limit worker exposure problems and any plant stress issues.

Question 4. Since I have plans to inject Ridomil Gold through the drip after planting my plugs (I am thinking about 1 week after transplanting), don't you think that it would be better to use Ridomil in that way, or do I also need to make an application with Ridomil to the plug trays before planting?

Answer 4: Ridomil is clearly not labeled for use in plug production facilities. The label specifically prohibits use in transplant trays, as a foliar application or in transplant water. There are two good reasons for this – possibly among others. First, Ridomil use prior to field setting strawberry transplants can result in slow grow-out of the plants once they are field set. Second, resistance to the fungicide can develop easily as use in transplant facilities favors the development of resistant populations which then get transferred to the field – a serious issue for future control of the pathogen in the field. Resistance to the phosphite fungicides is much less common.

Ridomil is a superior product in the beds. If growers cannot set up their drip irrigation system prior to or right after planting, then Ridomil can be incorporated into the beds when beds are being formed. This was the case for a grower who asked today. Application during bed formation in pepper fields that had Phytophthora problems worked better than applying Ridomil through the drip after planting but no data is available for strawberries. If excess overhead irrigation is not required, the product could be injected into the beds though the drip tape prior to planting. Finally, alternatively and the method most growers seem to prefer, Ridomil can be applied into the beds when excess overhead watering is done and when plant roots begin new growth (5-7 days after planting). If the transplants were not treated, the sooner the Ridomil is in the bed the better keeping in mind it will wash down into the soil if excess overhead watering occurs and will not be absorbed if the roots are not active. Detailed studies on timing for strawberries are not available. Ridomil should be considered again as a second application in the early spring when new plant growth starts. Strawberry plants grow lots of roots right at this time and protection is critical during early spring growth.

Question 5. I am having difficulty in my area in finding Aliette, so my question is whether the other Phosphites listed in the SR SFC IPM Guide are just as effective as Aliette, and should I stick with the rates suggested in the 2011 IPM Guide? I have heard that the Phostrol label calls for rates of 3.75-5.0 pints/acre when disease pressure is severe?

Answer 5. Overall, the phosphite chemistries are very similar in terms of their efficacy. Different rates relate to different concentrations of the active ingredient and in a plug facility there is concern about using high rates. In NCSU trials, we know Prophyt, Aliette and another similar product were all equally effective. In turf studies, some phosphites did prove superior to others and this is likely related to formulation but the differences were minor.

Question 6. Is there any advantage to mixing other materials with Aliette (e.g. potassium carbonate)?

Answer 6. Potassium carbonate is used to adjust the pH of the spray mixture and this protects against plant injury problems when Aliette is used before or after other products such as copper. There is no advantage to tank mixing with other products and there may be real disadvantages with mixing other products due to the presence of surfactants or other compounds that result in plant injury when combined.

Question 7. What is your general impression about the availability of extra tips this season?

Answer 7. Growers can certainly "check around" but the thing worth stressing is that in the tip and plug nursery business, it is very unusual to find much extra supply in any season, as these are grown under contract (very little speculative production). Used correctly, it is possible to "manage this problem", and with the products mentioned in this advisory, it is possible to turn this problem around. However, as Powell Smith says, Time is of the essence. We have seen low plant death problems where plants have been treated in accordance with the observations above. Although there is no experimental data, it makes sense to remove healthy plants or rogue out diseased plants to prevent the pathogen from spreading more. Excess free water in the and around the trays should be avoided and don’t work plants when wet. Moving plants from an infested plug facility, even if symptoms are no longer present, will introduce the pathogen into the field soils. Many farms already have Phytophthora in the field but this can be a long term risk, especially in fields where the highly susceptible variety Sweet Charlie will be planted in future years.

Fresh Market Vegetable and Tomato Field Day Tomorrow

Tomorrow, Thursday August 4 is the Annual Fresh Market Vegetable and Tomato Field Day at the Mountain Horticultural Crops Research Station in Mills River.

The annual tomato field day at the Mountain Horticultural Crops Research Station in Mills River! This is your opportunity to see new up and coming varieties and learn the latest about disease, insect, and weed control for staked tomato production and vegetables in western North Carolina. As always, the afternoon field day will be followed by a pig pickin' at Lake Julian.

The field day begins at noon and pesticide credits will be offered.

To view the complete program click here.

Tomato field day is sponsored by North Carolina State University, College of Agriculture and Life Sciences, NC Agricultural Research Service and NC Cooperative Extension Service, the North Carolina Department of Agriculture and Consumer Services, and the North Carolina Tomato Growers Association. For more information, contact Denny Thompson at 828.684.7197 or Jim Walgenbach at 828.684.3562.

Downy Mildew Confirmed in Buncombe County

Downy mildew has been confirmed at very low levels in a 2-acre cucumber field in Buncombe County. Growers are encouraged to begin treatment.

Review this post from June on the current recommendations: Pest News June 24

Don't forget to review the Cucurbit Downy Mildew Forecasting website for more information.

NC Pest News for June 3

Squash bug adults feeding on the stem of squash. Squash bugs love to hide below plastic!

Squash bug nymphs just hatched from bronze eggs.

This week's issue of NC Pest News is now available. It includes a review of strawberry disease issues from 2011 and the vegetable insect update. The insect update discusses the pest in the photo above, the squash bug. We have been seeing many squash bugs in WNC as of late, as well as cucumber beetles, a few stink bugs and thrips.

You can receive vegetable pest updates from North Carolina State University via Facebook (NCSU Vegetable Entomology) and Twitter (ncsuveg).

Check out these cucumber beetles feeding on summer squash! (below).


To view past issues of NC Pest News click here.

South Carolina: Downy Mildew Found on Cucurbits in Home Garden Center

**No cucurbit plants infected by downy mildew have been identified in NC big box stores, but growers and home owners should always inspect transplants before purchasing**

Earlier this week, Dr. Anthony Keinath at Clemson sent the following report to agents:

"My technician found cucurbit downy mildew (CDM) on yellow summer squash and zucchini plants at a Home Depot store in Charleston, SC on Wed. 4/6/11. There were several plants at bloom stage in 1-gallon pots with spots of downy mildew on about 25% of the leaves. Several CDM spots had begun to sporulate. (The plants also had powdery mildew, which was more severe than CDM.) The plants were grown in Miami, FL, and labeled with Home Depot tags. The garden manager pulled all of the remaining plants. However, it appears that some diseased squash plants were purchased between Wed. and Sunday, when I confirmed CDM.

Please check your local Home Depot store to see if they also had a shipment of diseased squash plants. These plants could be the start of an early epidemic of CDM in your area! If you find any diseased plants, please let me know. (Squash plants with powdery mildew only also should not be sold.)"

Dr. Keinath put together an informational fact sheet on this problem including control recommendations. Timely Talk: Cucurbit Downy Mildew.

Please revisit my blogpost from April 22, 2010 on diseases in home garden centers entitled "Don't Bring Problems in With Transplants! "

Use the "Search WNC Veggies" application at the top of the right hand menu to find pictures and descriptions of cucurbit downy mildew.

Researchers Taking Bite Out of Late Blight

Late Blight on Tomato Leaf

• The North Carolina State effort will focus on the development of an online national late blight reporting and alert system.

• The system, which will show farmers late blight outbreaks across the nation, will include what is known as decision support information on how best to deal with the disease.

North Carolina State University scientists will be heavily involved in a national effort to help farmers better manage a plant disease called late blight, which can decimate tomatoes and potatoes.

Jean Ristaino, a professor of plant pathology in the College of Agriculture and Life Sciences at North Carolina State, and Ryan Boyles, state climatologist and director of the State Climate Office of North Carolina, which is located on North Carolina State’s Centennial Campus, are part of a $9 million, 5-year U.S. Department of Agriculture effort to give farmers better tools to use in dealing with late blight. The effort is being led by the University of California at Riverside but will involve scientists across the nation.

Ristaino said the North Carolina State effort will focus on the development of an online national late blight reporting and alert system. This system, which will show farmers late blight outbreaks across the nation, will include what is known as decision support information on how best to deal with the disease.

Late blight, which is caused by a pathogen called Phytophthora infestans, infects American tomato and potato crops every year, Ristaino explained, but various factors, including weather, determine whether the disease causes significant crop losses from year to year.

The disease was particularly bad in 2009, she added, when cooler than normal temperatures and abundant rainfall helped spread late blight. In 2009, late blight destroyed much of the tomato production in the northeast U.S.

Ristaino said growers can protect their crops from the disease if they apply fungicide prior to a disease outbreak and if they apply the correct fungicide.

The system that Boyles and Ristaino are developing is designed to give farmers the information they need to protect their crops from the disease.

The state climate office will develop an online map that will use information from monitoring teams around the nation to locate late blight outbreaks.

Usually begins in Florida Ristaino said that on the East Coast, the disease typically begins each spring on tomatoes in Florida and then spreads to other areas by weather events.
The spores that cause the disease can be carried on the wind, although Ristaino said that in 2009 most pathogen movement was the result of the shipment of infected plants from one part of the country to another.

The severity of the disease also depends to a large degree on the strain, or type, of late blight. Working with scientists at Cornell University in New York, Ristaino will determine the type of late blight found in farmer’s fields. Ristaino said 24 different late blight strains, or genotypes, have been found in the United States, and some of these strains tend to damage one crop, either
tomatoes or potatoes, more than the other.

At the same time, different strains are more or less susceptible to different fungicides. In 2009, five different strains were found on tomatoes and potatoes, but one particular strain, US-22, did most of the damage, she added.

When reporting teams across the country find the disease, they will send samples to Cornell and North Carolina State and to Oregon State on the West Coast. At North Carolina State, Ristaino’s lab will determine the disease genotype. This information along with the location of the disease will be available through the online map.

The late blight website will also include information on how best to protect crops from the disease. Ristaino added that as she and other scientists identify late blight strains they should be able to track the development of strains that are resistant to various fungicides, information that should be extremely helpful in aiding farmers in managing the disease.

Ristaino said the project also includes an educational component. Summer internships will be available to undergraduate students who wish to work on the project.

The reporting and alert system is expected to be operational for the 2011 growing season, and Ristaino said she expects to begin receiving disease samples in early May.

She added that the disease typically moves up the East Coast as the growing season progresses. Late blight is usually found on North Carolina potatoes in June, while it’s usually found on tomatoes in western North Carolina in late July and August.

This year, farmers should be better prepared than in the past when late blight makes its annual appearance.

Source URL: http://southeastfarmpress.com/vegetables/researchers-taking-
bite-out-late-blight

2011-04-08
Byline: By Dave Caldwell, North Carolina State University

Late Blight Confirmed on Tomatoes In Henderson County

Late blight has been positively identified in Henderson County on tomatoes. With the afternoon showers and reports from other parts of the eastern U.S. it was only a matter of time.
Growers are encouraged to scout their fields and begin with control measures.

Sorry I don't have a lot of time to put details in this afternoon, but review my post from last year for some basic information.

Recommendations for conventional producers are chlorothalonil as a preventative if late blight is not found in your field or nearby. If late blight has been identified in your field applications of cyazofamid (Ranman at 2.1-2.75 fl oz/acre), fluopicolide (Presidio at 3-4 fl oz/acre) or mandipropamid + difenoconazole (Revus Top at 5.5-7 fl oz/acre) are recommended. Always read and follow the label when using pesticides! The label is the law.

For organic recommendations, see this article from Alex Stone on eXtension.

More to be reported later. Sorry again for the short note.

UPDATE 1 PM:
This just in from NCSU Plant Pathologist Dr. Kelly Ivors:

"Hey Everybody-

This morning we found and confirmed late blight (by microscopic examination) in one small shaded area of a conventional tomato field in Henderson County. We have not been able to confirm its presence anywhere else in the tomato production areas of NC this summer, so I believe this is the start of the tomato late blight epidemic in WNC. We've had some rains recently and I'm sure it's out there elsewhere now, or soon to arrive.

Fungicide recommendations for controlling late blight on fresh market tomatoes start at week 9 in the NC tomato foliar fungicide guide.

It can be found at this link.

http://www.ces.ncsu.edu/fletcher/programs/plantpath/tomato-spray-guide/tomato-spray-guide.pdf

In addition, there is information (fact sheet) on this disease in North Carolina, including pictures of the symptoms at this link.

Check out the different diseases and select the one under Tomato Late Blight.

http://www.cals.ncsu.edu/plantpath/extension/fact_sheets/index.htm

Please make sure to get your preventative sprays on as soon as possible if you grow tomatoes in late blight prone areas. Chlorothalonil works well as a protectant if you do not yet have the pathogen in your field. If already established in your tomato field, it would be best to apply something more than a protectant like Presidio (+ chlorothalonil) or Ranman.

If you need a confirmation of late blight in your fields, please do not hesitate to call your agent or my lab to submit a sample.

Thanks

Kelly"

WNC Strawberry Pre-Plant Meeting, July 28

It's hard to believe its already time to start planning for the 2011 strawberry season!

Planting will start in a few short weeks so come and get some great tips and information on strawberry production at the WNC Strawberry Pre-Plant Meeting. Details below.

What?: WNC Strawberry Pre-Plant Meeting When?: Wednesday July 28, 6:30 pm

Where?: Mountain Horticulture Research and Extension Center, 455 Research Dr. in Mills River, NC

Who should attend?: All strawberry producers who are looking for the most up-to-date information on strawberry production in WNC and the entire region.

Agenda:

1. Day neutral varieites and high tunnel production for WNC - Dr. Barclay Poling, NCSU Dept. of Horticultural Science. Work is sponsored by the Tobacco Trust Fund.
2. Integrated Pest Management for Strawberries - Dr. Hannah Burrack, NCSU Dept. of Entomology.
3. Disease Management and Fumigation Changes - Mr. Rob Welker, NCSU Dept. of Plant Pathology

1.5 Pesticide Credits are available in the categories of N, O, D and X

Downy Mildew on Cucumber in WNC

Well, this has been a very exciting week to be a plant pathologist! First, downy mildew on basil, now downy mildew on cucumbers.
*These are two different disease problems, just because they have the same name DOES NOT mean that these two disease are caused by the same organism and will cross-infect one another!*

Cucurbit downy mildew, caused by pathogen Pseudoperonospora cubensis, has been confirmed on pickling cucumbers in Henderson County. Growers are advised to scout their cucurbit plantings which include cucumber, squash, melons and other gourds. Last year we found the downy mildew in Henderson County late in July.

Symptomatic downy mildew cucumber leaf. Angular lesion are first light green and then turn brown with age.

The underside of a downy mildew infected cucumber leaf. You can see the dark spores of the pathogen as they arise from the angular lesions which are bound by the leaf veins.

Downy mildew of cucurbits has the potential of spreading very quickly. Its wind-borne spores can spread easily throughout the region - especially on cloudy days. The pathogen prefers cool temperatures and wet conditions, which we certainly have not had in WNC as of late! I believe that recent hot, dry and sunny conditions are the reason that the downy mildew on cucurbits is not widespread at this time. For example, large cucumber plantings just miles away from where I initially found the disease are unaffected at this time.

With rain possible this weekend, it is very important to prevent downy mildew from infecting your cucurbits, especially cucumber. Growers are advised to protect their plants using fungicides. For conventional producers, review the June 4th North Carolina Pest News or review my blogpost from June 2009 for control recommendations.

Management of downy mildew on cucurbits is tricky for organic producers. There are a number of OMRI-listed products that are labeled for the control of downy mildew on cucurbits, including copper, OxiDate, Serenade and neem. In research studies, copper products were proven to be the best option (only option, really) for managing downy mildew on cucurbits. Copper is only efficacious in plants that are not yet infected or exhibit only mild symptoms.

Visit the Cucurbit Downy Mildew Forecasting Website to see where the disease is currently located and where the team predicts it to show up next.

If you need help diagnosing a problem on your cucurbits, please contact your local NC Cooperative Extension Office.

To see more pictures of the downy mildew on cucurbits and to learn more about the disease, visit my previous posts.

Basil Downy Mildew

Sporulation of Peronospora behlbarii, causal agent of basil downy mildew.

Basil downy mildew is a new disease that has been causing headaches for growers in the eastern US for the past two seasons. Basil downy mildew was reported in South Florida in October 2007. This disease has the potential to be very destructive to basil producers. European producers have been dealing with the disease since 2001. The disease is thought to have been introduced in the US from infected seed from Europe

The first confirmed case of the disease in NC occurred last summer in Chatham County. Agriculture agent, Debbie Roos, did a great post on the diseases with wonderful pictures last August.

The disease has been found in several locations in WNC this year. This is surprising because we have been so hot and dry and downy mildew pathogens tend to like cooler temperatures and wet and humid conditions. Apparently, basil downy mildew is the exception - it likes moderate to warm temperatures!

Basil downy mildew is so devastating because the discoloration of the leaves makes the basil unmarketable. Eventually the leaves will become black or necrotic and die completely.

Slight yellowing of basil plants that are infected with Peronospora behlbarii, causal agent of basil downy mildew.

Discoloration of basil leaf caused by downy mildew.

The basil downy mildew pathogen, Peronospora belbahrii, is spread by contaminated seed, marketing infected plants or leaves and wind-borne spores. This pathogen also infects other plants of the Lamiacea family which inculdes basil, sages, and mints. The spores of the pathogen are abundant on the underside of the leaf.

Discoloration of basil leaf caused by downy mildew, P. behlbarii.

Notice the fuzzy growth on the underside of the leaf. This was the first tip that what we were dealing with was downy mildew. Also, note the black dying tissue.

Dark sporulation of the pathogen P. behlbarii that causes downy mildew on basil on the underside of the leaf.

This disease can often be mistaken for sunburn on basil leaves, which I have also noted this year.

Sunburned basil leaves.

There is a similar downy mildew pathogen that infects coleus, but this pathogen has been shown to be genetically different than the pathogen on basil and the ornamental hosts are no longer considered alternative hosts to the basil disease. To read more about the specifics of basil downy mildew, visit Cornell Plant Pathologist Dr. Meg McGrath's on-line factsheet Basil Downy Mildew - A New Disease to Prepare For.

Management of basil downy mildew requires an integrated approach. Using seed that is not contaminated with the pathogen, selecting less susceptible varieties and applying fungicides are the primary practices. Management should also include increasing airflow through the plant canopy in order to minimize leaf wetness and humidity in order to suppress the disease. This is especially true in greenhouses. Dr. McGrath outlines management steps, including variety trials from New Jersey, in her factsheet.

Fungicides used for downy mildew on basil include OMRI-approved Actinovate and OxiDate, which are labeled for use. Many other conventional fungicides do not yet have the label required to control this disease on basil, with the exception of K-Phite and ProPhyte. It is expected that this will change in the near future. Fungicides should be applied frequently and prior to first symptoms if possible in order to control downy mildew on basil effectively. This is of course tricky, especially in areas without history of the disease.

If you suspect that you have downy mildew on your basil, visit your local NC Cooperative Extension office for help identifying and reporting the disease.

Webinar 7/1: Late Blight Management on Organic Farms

There is still time to register for tomorrow's 2010 eOrganic Late Blight Webinar!

Are you an organic producer who battled with late blight last year? Late blight hasn't been found in NC, yet, but if you want some tips and to learn management options for late blight control, this webinar is just for you.

What: Late Blight Management on Organic Farms 2010

When: July 1, 2010 at 8 PM Eastern Time (7 PM Central, 6 PM Mountain, 5 PM Pacific)

Space is limited.

Click here to register
http://www.extension.org/article/28346

Late blight reached epidemic proportions on U.S. farms in 2009. Join eOrganic presenters Dr. Sally Miller of Ohio State University and Dr. Meg McGrath of Cornell University for a free Webinar to hear an update on late blight in 2010. Learn about the late blight disease cycle, how to scout and diagnose the disease, and how to manage late blight on organic farms.

Thank you and hope you can make it!