Rutgers University | New Jersey Agricultural Experiment Station | Pesticide User Responsibility

Andy Wyenandt

This is an archive of Dr. Wyenandt's posts on the Plant and Pest Advisory.

September 20, 2016

Best management practices for reducing Dickeya dianthicola in potato in NJ.

As the potato season is winding down in New Jersey (and other states in the mid-Atlantic region), it is time to begin thinking about sourcing seed for next season. Below is a list of best management practices to help reduce the chances for Dickeya dianthicola in your potato operation.

  1. All potato growers are strongly encouraged NOT to purchase those varieties (with lot numbers) which are known to have Dickeya from any source.
  2. All potato growers are strongly encouraged not to purchase seed from those growers/brokers with a known history of Dickeya.
  3. Potato growers SHOULD NOT rely on Blackleg tolerance levels reported on the North American Seed Health Certificates or the Florida Test results for presence of Dickeya in ANY seed lot from ANY source.
  4. Ask the grower/supplier if the field of seed origin was rogued for “Blackleg”.
  5. Any grower which rejects a load of seed for suspect Dickeya should report information to your local Extension Agent, Extension Specialist, or Potato Growers Assoc.
  6. Request PCR testing for Dickeya dianthicola from supplier (directly from grower/or broker) using an independent lab. Reject any load if no Dickeya test results are available or those seed lots that have tested + for Dickeya.
  7. Growers are encouraged that each truckload brought to the farm operation be sampled and re-tested for Dickeya once delivered. All results should be reported to your local Extension Agent, Extension Specialist, and/or Potato Growers Assoc.
  8. All growers are encouraged to report every variety, lot number (North American Seed Cert), field (general) location, and testing results each spring so Dickeya can be tracked and that this information be publically available to all potato growers in and out of the state.
  9. Fields with a known history of Dickeya should not be planted back into potato for at least 3 years or longer. Avoid planting brassicas and onions in potato rotations, especially in fields with a history of Dickeya.
  10. Growers using surface water (pond or stream) should be encouraged to do monthly water testing for Dickeya, especially if water source is near field with known Dickeya infestation.
  11. Wash/dump water needs to be displaced in an area away from packing shed, particularly those sheds near any production field or source of ground water that may be used for irrigation.
  12. Culled fruit needs to be dumped away from any production field, source of ground water, or any area where contamination of equipment may occur.
  13. All potato growers with fields with Dickeya-suspect symptoms need to be sampled and tested during the growing season.
  14. Rogue or volunteer plants appearing in fields with known Dickeya infestation the previous year or any prior year need to be removed, and/or sampled and tested if “Blackleg” symptoms present.
  15. All equipment during seed piece cutting needs to be disinfested on a regular (daily) basis, and/or disinfested between lot numbers and/or varieties. Quaternary ammonium is a good option for this purpose.

Remember, after doing your due diligence if you as a customer are not satisfied with the seed or information regarding the seed you should seek another source. Dickeya dianthicola has been reported in 16 states (DE, FL, MD, MA, NJ, NY, NC, PA, RI, VA, WV, OH, IN, MO, MI, and TX) on at least nine potato varieties to date in 2016. These varieties include: ‘Reba’, ‘Superior’, ‘Vivaldi’, ‘Norwis’, ‘Snowden’, ‘Yukon Gold’, ‘Beacon Chipper’, ‘Kennebec’, and ‘Atlantic’. Tuber and water test results are still forthcoming. Known sources of infested seed have originated from New Brunswick, Canada and Maine in our state and region this summer. In some cases, multiple varieties of Dickeya-infested seed have originated from the same source. Potato growers, crop consultants, and Extension personnel in states which grow and are still harvesting should remain vigilant by scouting their fields for Dickeya symptoms, particularly those varieties which have tested positive for Dickeya, on a regular basis and by submitting any suspect samples for diagnostic testing.

Dickeya dianthicola has been detected in the US in the past, and because of this, APHIS just recently announced that the pathogen has been designated as a non-reportable/non-actionable pathogen despite its potential to cause 100% crop loss. Thus, any seed originating from Canada or other regions in the US should be carefully vetted. A link to the USDA/APHIS website for information on Dickeya dianthicola detection and control can be found here. Importantly, there is no current policy in place designed specifically for regulating and/or controlling Dickeya dianthicola in potato in the US or Canada.

The best method for keeping your potato operation Dickeya-free is to adopt your own 0% Dickeya-tolerance policy.

 

Filed Under: Vegetable Crops Tagged With: ,
September 13, 2016

Vegetable Disease Briefs – 9/13/16

  • Cucurbit downy mildew has been confirmed on cucumber in New Jersey. To date, cucurbit downy mildew has been reported on cucumber and melon in the mid-Atlantic region. Downy mildew is beginning to be reported on many other cucurbits in other parts of the country. All cucumber growers need to add a downy mildew-specific fungicide to their weekly fungicide programs. All cucurbit growers need to scout on a regular basis.
  • Pepper anthracnose is being reported in southern New Jersey.
  • Cucurbit powdery mildew is active on all cucurbit crops.
  • There have been no new reports of Late blight this this past week.
Filed Under: Vegetable Crops Tagged With: ,
September 6, 2016

Vegetable Disease Briefs – 9/6/16

  • Cucurbit downy mildew has been confirmed on cucumber in New Jersey. To date, cucurbit downy mildew has been reported on cucumber and melon in the mid-Atlantic region. All cucumber growers need to add a downy mildew-specific fungicide to their weekly fungicide programs. All cucurbit growers need to scout on a regular basis.
  • Dickeya dianthicola was confirmed in New Jersey on ‘Dark Red Chieftain’ originating from New Brunswick, Canada this past week. This is the third report of Dickeya on seed originating from Canada this summer. ‘Yukon Gold’ and ‘Reba’ from New Brunswick, Canada have also tested positive. In total, Dickeya dianthicola has been confirmed in 16 states to date. All potato growers are encouraged to scout fields and report any suspect plants/tubers. The best method for keeping your potato operation Dickeya-free is to adopt your own 0% Dickeya-tolerance policy.
  • Pepper anthracnose is being reported in southern New Jersey.
  • Cucurbit powdery mildew is active on all cucurbit crops.
  • There have been no new reports of Late blight this this past week.
Filed Under: Vegetable Crops Tagged With: ,
August 25, 2016

Vegetable Disease Briefs – 8/25/16

  • Cucurbit downy mildew has been confirmed on cucumber in New Jersey. To date, cucurbit downy mildew has been reported on cucumber and melon in the mid-Atlantic region. All cucumber growers need to add a downy mildew-specific fungicide to their weekly fungicide programs. All cucurbit growers need to scout on a regular basis.
  • Dickeya dianthicola has been confirmed in 16 states to date. All potato growers are encouraged to scout fields and report any suspect plants/tubers. The best method for keeping your potato operation Dickeya-free is to adopt your own 0% Dickeya-tolerance policy.
  • Pepper anthracnose is being reported in southern New Jersey.
  • Cucurbit powdery mildew is active on all cucurbit crops.
  • Late blight was reported on tomato near Blacksburg, Virginia this past week.
Filed Under: Vegetable Crops Tagged With: ,
August 22, 2016

Dickeya dianthicola reported in 4 more states: IN, MO, MI, and TX

Dickeya dianthicola has been reported in four more states (Indiana, Missouri, Michigan, and Texas). Using PCR test results and North American Certified Seed Potato Health Certificates to track Lot no., Dickeya dianthicola has been reported in 16 states (DE, FL, MD, MA, NJ, NY, NC, PA, RI, VA, WV, OH, IN, MO, MI, and TX) on at least nine potato varieties to date in 2016. These varieties include: ‘Reba’, ‘Superior’, ‘Vivaldi’, ‘Norwis’, ‘Snowden’, ‘Yukon Gold’, ‘Beacon Chipper’, ‘Kennebec’, and ‘Atlantic’. Test results and additional information are still forthcoming. Known sources of infested seed have originated from at least two suppliers in Canada and 11 seed suppliers in Maine. In some cases, multiple varieties of Dickeya-infested seed have originated from the same source in Maine. Potato growers, crop consultants, and Extension personnel in states which grow and are still harvesting potatoes from Maine or New Brunswick, Canada should remain vigilant by scouting their fields for Dickeya symptoms, particularly those varieties which have tested positive for Dickeya, on a regular basis and by submitting any suspect samples for diagnostic testing.

Dickeya dianthicola has been detected in the US in the past, and because of this, APHIS just recently announced that the pathogen has been designated as a non-reportable/non-actionable pathogen despite its potential to cause 100% crop loss. A link to the USDA/APHIS website for information on Dickeya dianthicola detection and control can be found here. Importantly, there is no current policy in place designed specifically for regulating and/or controlling Dickeya dianthicola in potato in Maine or Canada.

The best method for keeping your potato operation Dickeya-free is to adopt your own 0% Dickeya-tolerance policy.

 

Filed Under: Vegetable Crops Tagged With:
August 17, 2016

Cucurbit downy mildew update: 8/17/16

The extremely hot, dry weather in areas of New Jersey and the region has kept downy mildew in check the past few weeks. To date, cucurbit downy mildew (CDM) has only been detected on cucumber (Cucumis sativus) in the state. It has been found on cucumber and cantaloupe (Cucumis melo) in southeast PA, the eastern shore of Maryland, and in southern VA. Cucurbit downy mildew has also been reported on butternut squash (Cucurbita moschata) on the eastern shore of VA. Further south it has been reported on watermelon (Citrullus lanatus), cucumber, and cantaloupe  in North Carolina. In South Carolina, CDM has been reported on acorn and summer squash (Cucurbita pepo), cucumber, butternut squash, and giant pumpkin. All cucurbit growers are encouraged to scout on a daily basis. Maintenance applications for powdery mildew should already be initiated for all cucurbit crops. Downy mildew specific fungicides should already be incorporated into weekly maintenance applications for cucumber and cantaloupe. Growers of pumpkin, winter and summer squash, and watermelon should remain diligent and scout on a regular basis and begin to consider adding downy mildew specific fungicides into weekly maintenance programs as we head into the fall.

Filed Under: Vegetable Crops Tagged With: