Fighting bacterial wilt with row covers Erika Saalau and Mark L. Gleason Plant Pathology Department Iowa State University

 Transplanted in May-June  First harvest by August  Early muskmelons = premium prices

 Adult beetles overwinter near fields  Become active in May  Look for young cucurbits  Feed, reproduce, lay eggs  Next generation emerges in fields

 Caused by Erwinia tracheiphila  Transmitted by cucumber beetles  Plants wilt and die

Overwintering adults Cucurbit seedlings Transmission Symptoms Beetles reproduce Acquire bacteria

How do plants become infected with the disease? ??

 Early!!!  Highest risk period= early beetles

 Managing beetles!!!  Insecticides  Trap crops  Baited traps  Row covers Management

Why row covers?  Protect from frost and extreme weather conditions  Increase earliness and yield  Prevent insect damage  Protect from bacterial wilt!!!

How do they work?

What about pollination?  Timing of removal  Conventional removal= flowering  Could row covers stay on a bit longer?

 Open row cover ends for pollinators  Add bumblebees  Remove row covers 10 days after flowering

 Plants were covered from transplant  No insecticides were applied!

No Row Cover Remove covers at flowering No Row Cover At flowering: Open ends Add bumblebees

No row covers Row covers anthesis Delayed-removal row covers

 Delaying removal by 10 days can provide season-long protection against bacterial wilt.  This strategy can reduce the need for insecticides.

No row covers Row covers

 All row cover treatments suppressed bacterial wilt

 No beetles! =  No disease

Delayed RC None RC removed at bloom None RC removed at bloom

 Sporadic disease in the Midwest  Delayed-removal strategy may provide consistent returns.

Do you feel lucky?

 Cost effectiveness is affected by how often bacterial wilt outbreaks occur.  Delayed-removal strategy was advantageous when wilt occurred ≥ 50% of the growing seasons.

 USDA's Organic Research and Extension  Pennsylvania, Kentucky, and Iowa