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.

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.