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!

Pest News: May 18th

The latest edition of NC Pest News is now available.  You can find it and all other archived editions here.

In this edition vegetable and fruit growers may find these articles of interest:

1. Brown Marmorated Stink Bugs
2. Thrips in Cucurbits
3. Squash Bugs
4. Soil Insect Management in Sweetpotato

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.

NC Pest News for July 22

Sorry this is a little late. The latest edition of NC Pest News is now available.

In the July 22 issue:

1. My tomato plants are wilting...then they die
2. New website to report brown marmorated stink bug sightings in North Carolina

Pest New July 15

The latest edition of NC Pest News is now available.

In this edition you'll find:

• Plant Disease and Insect Clinic Information on the Internet
• Worm Control in Sweet Control: 2011 Edition

July 15 Edition of NC Pest News.

New Pests: Spotted Wing Drosophila and Kudzu Bug

There are two new insect pests that growers need to be aware of, spotted wing drosophila and the kudzu bug.

Spotted wing drosophila (SWD) is an invasive fruit fly pest of soft-skinned fruit (strawberry, blueberry, blackberry, raspberry, etc.). SWD was first observed in California in 2008 and then identified in 2009. In 2010, Dr. Hannah Burrack of NC State began an intensive monitoring plan for SWD in the Southeast. SWD was captured in NC and SC late 2010. SWD gets its name because the males have two spots on the end of their wings (one on each). Female SWD do not have spotted wings, but do have a serrated oviposter. This serrated oviposter allows the female to lay eggs in sound fruit, unlike common fruit flies which prefer decaying fruit. Because of this, SWD has potential to be an economically limiting crop.

SWD trapping is well underway throughout NC, in fact SWD was captured in Henderson County in mid-June. Small fruits producers are encouraged to start a monitoring program. Dr. Burrack explains how to construct and monitor SWD traps and how to identify them.

For treatment considerations, visit Dr. Burrack's post What to watch for: When treating SWD.

To read more about SWD or to view images, please visit Dr. Burrack's SWD page on her NC Small Fruits, Specialty Crops and Tobacco IPM blog.

If you would like assistance with monitoring, please contact me at sue_colucci@ncsu.edu or your local extension office.

Kudzu bug (adult) on soybean leaf.

Multiple kudzu bugs (adults) on soybean stem.

The next pest is the kudzu bug. This pest prefers legume crops, especially soybeans, but has also been observed feeding on potatoes, cotton and wheat. The kudzu bug was confirmed in central Georgia in 2009 and then spread throughout the state and to neighboring states in 2010. This pest has been identified in many NC counties, including Buncombe and Henderson Counties on soybeans. This pest isn't thought to be a problem on most vegetables, but those who grow edamame soybeans or potatoes should be concerned. The kudzu bug is a stem and leaf feeder, so far there have been no reports of the kudzu bug feeding on blooms or pods.

Based on Georgia data the economic threshold is one bug per sweep with large nymphs present, or three bugs per plant with large nymphs present. This pest is very mobile and will re-invade after treatment, so capturing or observing nymphs is important. According to the latest edition of NC Pest News, killing this pest has been relatively easy with conventional insecticides except the neonicotinoids (kudzu bug seem to be attracted to areas that have been treated with neonicotinoids). For organic producers, PyGanic is recommended. Other options are options are azadirachtin (Azagard) or kaolin clay (Surround), but the efficacy of these products is unknown.

To read more about the pest, see more pictures and a map of kudzu bugs movement in the southeastern US, see the June 24th of NC Pest News.

Pest News June 24

The latest edition of the NC Pest News is now available.

In this latest edition:

1. Cucurbit downy mildew recommendations for 2011
2. Cucurbit powdery mildew recommendations fro 2011

Cucurbit downy mildew has been found in NC in more eastern counties. It has not been found in WNC, yet. We are actively scouting as afternoon thundershowers and storms from the south could provide inoculum and suitable conditions for disease development. There have been no forecasts on the Cucurbit Downy Mildew Forecasting Website for disease development in our area. However, if you think you have this disease, please visit your local extension office for confirmation.

Downy mildew symptoms on cucumber leaf.

Downy mildew sporulation on the underside of a cucumber leaf.

The fungus that causes cucurbit powdery mildew is a very different pathogen than the water mold pathogen that causes cucurbit downy mildew. Cucurbit powdery mildew likes warm, humid conditions (the humidity within a plant canopy provides ideal conditions). The pathogen does not like wet conditions, but water will spread the pathogen spores to other plants.

Powdery mildew on a squash leaf.

Powdery mildew on the stem of a squash plant.

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.