Late Season Brings Prime Environmental Conditions for Disease on Southeast Vegetables

By The Certis Team

Late summer brings ideal conditions for bacterial and fungal disease outbreaks in Southeast vegetable crops, a critical time just before harvest. The combination of high daytime temperatures with limited cooling overnight, ample moisture from rain or dew and dense canopies with reduced air circulation create a perfect environment for significant infections.

Knowing what diseases are prevalent in their crops at this time and the conditions that contribute to outbreaks allow growers to make proactive, preventive fungicide/bactericide applications to limit the crop damage just prior to harvest.

As a good rule of thumb, vegetable growers should be sensitive to these high-risk environmental conditions that promote bacterial/fungal diseases on foliage:

• Afternoon rain that provides moisture
• Several cloudy or rainy days in a row preventing drying
• Extended high relative humidity (over 90%) that prevents the drying of moisture
• Nighttime temperatures, generally above 70º, allowing conditions that favor pathogen development and infection
• Heavy morning dew wetting foliage even without rainfall

Common Vegetable Diseases in Late Summer
and the Conditions that Favor Infection

• Downy Mildew: 60–75°F, relative humidity >95%, foliage is wet overnight
• Powdery Mildew: 70–85°F, relative humidity > 90%
• Early Blight: 75–85°F, wet foliage for 6–24 hours
• Septoria Leaf Spot: 68–80°F, extended leaf moisture from rain or heavy dew
• Bacterial Spot: 75–90°F, extended leaf moisture from rain or heavy dew
• Southern Blight: High temperatures (85–95°F), moist soils
• Anthracnose: Warm, wet weather during fruit ripening
  
  

What can growers do to protect their investment?

There are several agronomic steps growers can take to reduce their risk of bacterial and fungal diseases from causing significant damage to their crops, but by late in the season most of these options are not practical or possible. Decisions about overhead irrigation, stand thinning, varietal selection, crop rotation, and other cultural practices have likely already been made for the current growing season.

When faced with weather and environmental conditions favoring disease infection, growers are best served by making preventive fungicide/bactericide applications as their main line to maintain a healthy crop. During this late season/pre-harvest period growers need to consider fungicides with a 0-day Pre-Harvest Interval (PHI) restrictions, very short or no Re-entry Interval (REI) restrictions and no Minimum Residue Level (MRL) established if selling into restrictive markets.

Certis Biologicals has several fungicides/bactericides that fit these requirements and have been extensively field-tested and proven effective by vegetable growers.

Howler® EVO

• Multiple modes of action for preventive disease control
• Triggers Systemic Acquired Resistance (SAR) for additional disease defense
• Improves plant vigor to lessen effects of environmental stress and disease infection
• Five modes of action provide a wide spectrum of foliar disease control
• Activates both Induced Systemic Resistance (ISR) and Systemic Acquired Resistance (SAR) for broad disease prevention

• Major foliar diseases controlled*
  • Anthracnose, Downy mildew, Powdery mildew, Southern blight
• 0-day PHI
• No MRL, tolerance exempt
• 4-hour REI
  
  

LifeGard® WG

• Activates Systemic Acquired Resistance (SAR) to stimulate the plant's natural defense response against disease
• Provides preventive disease protection as part of an integrated disease management program
• Can be used as part of a resistance management program with other fungicides that have different modes of action
• Major foliar diseases controlled*
  • Bacterial spot, Bacterial speck, Early blight, Powdery mildew, Downy mildew
• 0-day PHI
• No MRL, tolerance exempt
• 4-hour REI
  
  

Double Nickel® LC

• Colonizes plant root hairs when soil-applied, helping prevent the establishment of disease-causing fungi and bacteria. 
• Major foliar diseases controlled*
  • Anthracnose, Bacterial leaf spot, Downy mildew, Powdery mildew,
    Southern blight
• 0-day PHI
• No MRL, tolerance exempt
• 4-hour REI
  
  

* Always consult product label for complete list of crops and diseases managed.

Interested in learning more?

Additional Product Resources:
For additional information on Howler® EVO, LifeGard® WG and Double Nickel® LC  including technical specifications and labeled use directions, please refer to the resources below. 

• Howler EVO: Tech Sheet | Product Label
  
• LifeGard WG: Tech Sheet | Sell Sheet | Product Label
  
• Double Nickel LC: Tech Sheet | Product Label
  
  

Always read and follow label directions. For a full list of protected crops and controlled diseases, visit the product pages and refer to the product labels.