Vegetable Disease Updates

June 14, 2024

Update on Cucurbit Downy Mildew ipmPIPE website and CDM Monitoring in Mississippi

The cucurbit downy mildew ipmPIPE website (http://cdm.ipmpipe.org), a disease-forecasting system for cucurbit downy mildew, was started in North Carolina in 2008, and from 2008 through 2022, was used not only to track outbreaks of the disease but to generate forecasts or risk-prediction maps of downy mildew occurring in a particular area. These forecasts were based on reported disease outbreaks and weather data and helped growers decide when it was necessary to apply a fungicide to manage downy mildew. Forecasts were suspended in 2023, but the website is still used to track confirmed reports of cucurbit downy mildew. Website visitors can sign up to receive customized text or email alerts when outbreaks of cucurbit downy mildew are confirmed within a designated proximity of a specified location. These reports can be used to help growers make more informed decisions about when to incorporate fungicides for downy mildew into a spray program.

Sentinel plots for cucurbit downy mildew were planted each spring and fall from 2016 through 2021 at the Truck Crops Branch Experiment Station in Crystal Springs (Copiah County), in the spring of 2016 and each fall from 2017 through 2021 at the North Mississippi Research and Extension Center in Verona (Lee County), and in the spring and fall in 2022 at the Beaumont Horticulture Unit (Perry County) to monitor for the occurrence of cucurbit downy mildew in Mississippi. Sentinel plots are plantings of one or more crops or varieties that are susceptible to a particular disease and that are monitored regularly for the occurrence of that disease. The purpose of the cucurbit downy mildew sentinel plots is to regularly monitor susceptible cucurbit hosts for downy mildew to detect when the disease first appears in and remains active in an area. Due to weather and limited resources, sentinel plots for cucurbit downy mildew have not been planted in Mississippi since 2023.

Cucurbit downy mildew has been detected each year in Mississippi since 2016, when monitoring efforts for this project began under Dr. Melanson. The disease has most often first been detected in August or September, but it has been detected as early as mid-June. Downy mildew is commonly observed in fall cucurbit crops in many areas of Mississippi by September. A summary of counties with confirmed reports of cucurbit downy mildew in Mississippi since 2016 is available online on the Monitoring and Reporting of Cucurbit Downy Mildew in Mississippi webpage. A searchable database for previously confirmed reports of downy mildew in Mississippi is available on the cucurbit downy mildew ipmPIPE website; reports list the host, county, date of report, date of first occurrence, and type of planting. 

Read more about this disease in the recently updated MSU Extension publication "Cucurbit Downy Mildew."

 

April 30, 2020

Update on 2019 Cucurbit Downy Mildew (CDM) Sentinel Plots and Reports, 2020 CDM Sentinel Plots, and CDM Forecasting and Reporting Website

By: Rebecca A. Melanson, MSU Extension Plant Pathologist, Central MS Research and Extension Center, Raymond, MS

In 2019, sentinel plots for cucurbit downy mildew were planted in the spring and fall at the Truck Crops Branch Experiment Station in Crystal Springs (Copiah County) and in the fall at the North Mississippi Research and Extension Center in Verona (Lee County) to monitor for the occurrence of cucurbit downy mildew in Mississippi. Sentinel plots included cucumber, cantaloupe, kabocha squash, acorn squash, butternut squash, and watermelon. Downy mildew did not appear in the spring sentinel plot at the Truck Crops Branch Experiment Station. The first confirmed reports of cucurbit downy mildew in 2019 in Mississippi were on winter squash and an unidentified cucurbit host in early September in Copiah County. Downy mildew appeared on all cucurbit hosts in the fall sentinel plot at the Truck Crops Branch Experiment Station and on all hosts, with the exception of kabocha squash, in the sentential plot at the North Mississippi Research and Extension Center.

A spring sentinel plot was planted at the Truck Crops Branch Experiment Station on April 2, 2020, and is being monitored each week. Sentinel plots for cucurbit downy mildew are also planned for the fall of 2020 at the Truck Crops Branch Experiment Station and the North Mississippi Research and Extension Center.

The Cucurbit Downy Mildew Forecasting and Reporting Website (https://cdm.ipmpipe.org/) has been updated! Forecasting has also begun for the 2020 growing season. If you wish to receive alerts on occurrences of cucurbit downy mildew within a specified distance of your location, please visit the “Alerts” page of the website. If you signed up to receive alerts prior to the website update, you will need to sign up again.

For more information on cucurbit downy mildew, see MSU Extension publication 3076 Cucurbit Downy Mildew, which was updated recently to include the 2019 update.

 

​April 16, 2020

Staying Connected and Available Resources - Friuts, Nuts, and Vegetables

By: Rebecca A. Melanson, MSU Extension Plant Pathologist, Central MS Research and Extension Center, Raymond, MS

• Building a Mississippi Vegetable, Fruit, and Pecan Producer List. Mississippi State University Extension Specialists are trying to build a list of commercial vegetable, fruit, and pecan producers to help improve our delivery of crop-specific and/or site-specific information to our Mississippi producers. We hope to use this list to email producers about upcoming events and new/updated resources as they become available. Please visit the Producer Registration Webpage (http://msuext.ms/nwslt) for more information about this effort and to add yourself to the list. Let us known what you grow and how you grow it!

• Vegetable Crop Handbook for Commercial Vegetable Production. We were able to get copies of the 2020 Vegetable Crop Handbook printed this year. Those involved in commercial vegetable production in Mississippi can request a FREE hard copy of the book by sending an email request to Janie Ross. Please provide your name, farm name, and complete mailing address. The 2020 Vegetable Crop Handbook is also available online. You can follow the link or visit www.vegcrophandbook.com to download a digital copy of the book. This is a new web address, so if you bookmarked the previous edition of the book, be sure to update your bookmarks. Remember, the focus of the Vegetable Crop Handbook is on commercial vegetable production. Vegetable production information for home gardens is available in The Garden Tabloid.

• Small Fruit Integrated Pest Management Guides for Commercial Production. The integrated pest management guides for small fruits (blueberry, caneberry, muscadine, bunch grape, and strawberry) have been updated for 2020 and are available on the Southern Region Small Fruit Consortium website (www.smallfruits.org). We are also in the process of printing a limited number of selected guides for distribution to our commercial small fruit producers in Mississippi. If you are in need of a hard copy of one of these guides to assist you in your commercial small fruit production, please select the appropriate link to send an email request for a FREE copy of the specific guide: Blueberry IPM Guide (Conventional), Caneberry IPM Guide, Muscadine IPM Guide, Strawberry IPM Guide. Please provide your name, farm name, and complete mailing address. Guides will be mailed out as soon as possible.

• Southern Region Small Fruit Consortium Newsletter. Mississippi State University is now a member of the Southern Region Small Fruit Consortium! We have been working with the Consortium to update various integrated pest management guides for a number of years, but our membership in the Consortium allows greater opportunity for small fruits research and agent training. The Consortium also sends out a quarterly newsletter, Small Fruit News, with articles covering various horticulture and pest management topics. Past issues are available at the Southern Region Small Fruit Consortium website on the News page. There, you can also subscribe to the newsletter to receive it directly in your email inbox!

• Outreach Through Social Media. If you are a social media user, consider “liking” or “following” some of our program pages/accounts to get updates, notices, and information!                                             

On Facebook: MSU Extension Diseases of Vegetables, Fruits, and Pecans (@MSUextDiseasesVFP) by Rebecca Melanson, MSU Extension Plant Pathologist                                              

On Twitter: MSU Extension Plant Diagnostic Lab (@MSUextPlantLab) by Clarissa Balbalian, MSU Extension Plant Diagnostic Lab Diagnostician

• Fruit and Nut and Vegetable Disease Extension Publications. A number of Extension publications on various fruit, nut, and vegetable diseases are available on the Fruit and Nut Disease Publications and Vegetable Disease Publications pages on the MSU Extension website. New publications are added when they become available, and new and updated publications are marked as such on these pages. A new publication recently added to this page is the publication “Bacterial Speck and Bacterial Spot in Tomatoes”. A number of other publications are in the process of being produced or updated, and I hope these will be available in the near future. Follow MSU Extension Diseases of Vegetables, Fruits, and Pecans on Facebook and register to be on our producer list to receive updates!

• MSU Extension Plant Diagnostic Lab Services. The MSU Extension Plant Diagnostic Lab will continue to operate during the Safer at Home order. If you are in need of plant disease diagnostic assistance or nematode services, please visit the MSU Extension Plant Diagnostic Lab website (https://extension.msstate.edu/lab) for information on how to submit samples. Walk-in clients are prohibited from entering the lab but may leave samples on the cart located outside the door. Digital images may also be sent by email to Clarissa Balbalian. Please contact the Diagnostic Lab if you have questions regarding sample submission and diagnosis. (Updated May 7, 2020)

 

May 29, 2018

Do Your Homework When Using Regional Pest Management Guides

By: Rebecca A. Melanson, MSU Extension Plant Pathologist, Central MS Research and Extension Center, Raymond, MS

     Regional pest management guides, such as the Southeastern U.S. Vegetable Crop Handbook and the Southeastern Peach, Nectarine and Plum Pest Management and Culture Guide, are excellent resources for commercial growers. These guides list products available for use against various diseases, insects, and weeds and often provide efficacy information for those products against specific pests.

     However, every product listed in these regional guides may not be registered for use in Mississippi. Before purchasing and applying a product, be sure that the product is registered for use in Mississippi. State registration information can be obtained from a number of online databases. Please see the MSU Extension publication Pesticide Label Databases for a list of databases that provide state registration information. And remember, the label is the law. Be sure to read and follow all label directions.

 

Clearing Up the Confusion: Plant Diagnostic Lab vs. Soil Testing Lab

By: Clarissa Balbalian, Diagnostician and Lab Manager, MSU Extension Plant Diagnostic Lab, Starkville, MS

     As sample submission season gears up, it is important to review the difference between services provided by the MSU Extension Plant Diagnostic Lab and the MSU Extension Soil Testing Lab as well as which forms should accompany samples submitted to these labs.  The Plant Diagnostic Lab analyzes soil for plant parasitic nematodes and plant tissue for disease.  The Soil Testing Lab analyzes soil for nutrients, pH, and soluble salts and plant tissue for nutrients.  The two labs handle samples in vastly different ways.  Please make every effort to submit your samples to the proper lab with the proper paperwork. This will help ensure the sample will be handled appropriately and will not accidentally be damaged to the point that it cannot be used for its intended purpose.

     The tables below outline the services provided by each lab and the form that should be used to accompany samples submitted to those labs. 

 

Plant Diagnostic Lab

190 Bost North, Rm. 09

Box 9612

Mississippi State, MS 39762

662-325-2146

Website: http://extension.msstate.edu/lab

Lab Director: Clarissa Balbalian

 

Service	Form*
Plant Disease Analysis	Plant Disease Sample Submission Form (F1139) (PDF)
Nematode Testing	Nematode Sample Submission Form (F448) (PDF)

*Forms are also available on the Plant Diagnostic Lab website.

 

Soil Testing Lab

190 Bost North, Rm. 01

Box 9610

Mississippi State, MS 39762

662-325-3313

Website: http://extension.msstate.edu/lawn-and-garden/soil-testing

Lab Director: Dr. Keri Jones

 

Service	Form*
Plant Tissue Analysis (nutrients)	Plant Analysis Form TTT
Soil Testing (nutrients, pH, soluble salts)	Soil Testing Laboratory AAA

*Forms are available from the Soil Testing Lab or your local county Extension office.

 

February 12, 2018

Cucurbit Downy Mildew Sentinel Plots and Reports in Mississippi

By: Rebecca A. Melanson, MSU Extension Plant Pathologist, Central MS Research and Extension Center, Raymond, MS

     Sentinel plots for cucurbit downy mildew (CDM) were planted in the spring and fall of 2016 and 2017 at the Truck Crops Branch Experiment Station (TCBES) in Crystal Springs (Copiah County) and in the spring of 2016 and the fall of 2017 at the North Mississippi Research and Extension Center (NMREC) in Verona (Lee County). The purpose of the sentinel plots is to have hosts that are susceptible to CDM available to regularly monitor for the presence of the disease in order to detect when it first appears in the area and is active. The sentinel plots are maintained to keep plants healthy as much as possible, but fungicides that have activity against CDM are not applied. Sentinel plots included cucumber (‘Straight Eight’), cantaloupe (‘Hales Best’), pumpkin (‘Big Max’), acorn squash (‘Table Queen’), butternut squash (‘Waltham’), and watermelon (‘Mickey Lee’).

Figure: Spring (2016) CDM sentinel plot at the Truck Crops Branch Experiment Station in Crystal Springs. Photo credit: R. A. Melanson, MSU Extension.

     In 2016, CDM was not observed on any hosts in either of the spring sentinel plots, but it did appear in the fall sentinel plot (butternut squash, cucumber). The first confirmed report of CDM in 2016 in Mississippi was on cucumber in late-August in Hinds County. CDM was also later confirmed in Copiah (cucumber, pumpkin, squash), Lee (pumpkin), and Madison (cucumber, squash) counties in 2016.

     The first confirmed report of CDM in Mississippi in 2017 was on cucumber in late June in the sentinel plot at the TCBES. This report was about two months earlier than the first confirmed report of CDM in Mississippi in 2016. CDM appeared on all cucurbit hosts in the 2017 spring sentinel plot by mid-July. CDM was confirmed in the fall sentinel plots at the TCBES (acorn and butternut squash, cantaloupe, pumpkin, watermelon) and the NMREC (all hosts) in 2017. CDM was also confirmed in Copiah (cantaloupe, pumpkin, watermelon), Hinds (cucumber), Simpson (cucumber), and Yazoo (pumpkin) counties in 2017.

     Sentinel plots for cucurbit downy mildew are planned for the spring and fall of 2018 at the TCBES and the fall of 2018 at the NMREC. If downy mildew on a cucurbit crop is suspected in Mississippi, please contact your local county Extension agent or Dr. Rebecca A. Melanson (rebecca.melanson@msstate.edu) so that samples can be obtained for disease confirmation and outbreaks of downy mildew can be reported.

     For more information on cucurbit downy mildew, please see MSU Extension publication P3076 Cucurbit Downy Mildew.

 

January 26, 2018

Sample Collection and Assistance for Disease Identification

By: Rebecca A. Melanson, MSU Extension Plant Pathologist, Central MS Research and Extension Center, Raymond, MS

     Diagnosis is the first step in disease management. It is important to know what disease and pathogen is affecting a plant or crop so that appropriate disease management actions can be taken. When seeking assistance from county agents or specialists, it is important to provide relevant information that can help your local county agent or specialist to identify the problem in a timely manner and determine the best management options. It is always a good idea to provide at least the following information: the affected plant host and variety, the extent of the damage, a description of the symptoms, and your preferences for disease management, which may range from conventional to strictly organic. Additional information such as disease history and recent pesticide use is also valuable.

     Often times, digital images (photos) of plants are also received from growers or homeowners wanting to know what is wrong with their plant. These images can be very valuable and provide additional information regarding a situation, but it is often not possible to diagnose a disease problem from a digital image. Information about the types of images that are most useful and examples of good images are available in MSU Extension publication P3022 Taking Photos of Plant Disease Problems. If sending photos to your local county agent or specialist, please remember to make sure that your photos are in focus and that you also provide the information requested above.

     Despite the valuable information that can be provided through words and images, it is often still necessary to examine a physical sample for diagnosis. Samples submitted for diagnosis should not be in an advanced stage of decay. They should also be fresh and arrive undamaged. Instructions for collecting and packaging samples for diagnosis are available in MSU Exteension publication M1562 How to Collect and Package Plant Disease Specimens for Diagnosis.

(The majority of this article originally appeared in the April 2017 issue of the North MS Fruit and Vegetable Newsletter.)