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Virginia Cooperative Extension
Natural Resources

Staff and volunteers with the Prince William Cooperative Extension’s Environment and Natural Resources program provide educational programs for individuals and business to implement sound practices producing aesthetically pleasing landscapes that have minimal negative impacts on the environment. Programs include:

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Here is a link to Watering Trees Podcast - Mature Tree

Seasonal Tips

The Environment and Natural Resources team and Master Gardener Volunteers of Virginia Cooperative Extension answer many questions throughout the year. Below are some of our most frequently asked questions for this time of year.

If you have additional questions, contact our Extension Horticultural Help Desk at 703-792-7747 or

Horticultural Tips:

It is not too late to participate in the BEST Lawns program.  For a $25 fee, we can measure and sample your lawn, develop a nutrient management plan tailored to your lawn and provide information to help improve the problems specific to your lawn.  For more information visit BEST Lawns on the Prince William County website.

Cool Season Lawns
For most people in our area have cool season (like bluegrass or fescue) lawns.  For cool season grasses an application of fertilizer in spring is largely unnecessary and likely to cause increased fungal problems as the weather gets warmer.

Cool season lawns will go dormant as we get into hotter weather.  Your grass doesn’t need to be watered if you allow it to go dormant.  If you prefer it stay green all summer, you can water it.  Water is best applied early in the morning. If you water deeply 1-2 times a week, your grass will be much stronger than if you water lightly everyday.  You will want to make sure your grass gets 1” of water per week from rain or your hose.  Once you commit to watering over the summer it’s important to continue watering.  Stopping and starting a watering program will only stress and weaken your turf.  Ultimately, water is better spent to high value crops like trees and vegetables. 

Mowing high (3-3.5”) will also help shade the soil and keep moisture in the soil longer.  Be sure to use a sharp blade and mow while the grass is dry. 

Warm Season Lawns

If you have a zoysia lawn, mid to late June is a good time to get your 1st fertilizer application on your turf. Remember over fertilizing zoysia can kill it so contact the VCE office for information on how best to fertilize your zoysia.

Weeds have sprung up in lawns and flower beds.  To best control unwanted weeds, identify them first before resorting to chemical control.  Use the following resources to identify them yourself or contact the Extension Horticulture Help Desk for assistance. 

Diseases and Insects:

While not complete, the following are diseases and insects that are more commonly found this time of year. Contact the Extension office for help with diagnosis and control recommendations.

Insects - Many insects are starting to appear in and around the house. Virginia Tech has factsheets on many common insects or call our Horticultural Help Line at 703-792-7747 for information on what's "bugging" you and the best and safest way to cure the problem.

Diseases -

  • Boxwood blight is a recently introduced fungal disease that causes severe defoliation and decline of susceptible boxwood. It was first identified in Virginia in a nursery location in Carroll County in 2011, but has been found in both landscapes and nurseries in several Virginia counties since then. VCE and the Virginia Department of Agriculture and Consumer Services partnered to form the Virginia Boxwood Blight Task Force (VBBTF) to provide leadership to protect Virginia’s boxwood nursery industry, historical gardens and landscape plantings from boxwood blight. The task force is developing Best Management Practices (BMPs) for boxwood blight for stakeholders potentially affected by the disease (e.g. boxwood producers, retailers, boxwood tip producers, professional landscapers, historic groundskeepers and home growers of boxwood). The task force solicited valuable input on the BMPs from representatives of the various stakeholder groups through meetings and electronic communication. The BMPs are available for download in PDF format at the VBBTF website.
  • Anthracnose: Lesions are usually quite large and follow the veins of the leaf. Trees may drop some affected foliage. These diseases normally occur on large trees and do no permanent damage – practice good sanitation by cleaning up fallen leaves. You may choose to apply a preventive fungicide treatments next spring. A certified pesticide applicator and certified arborist can make these treatments for you. Plants susceptible: ash, maple, sycamore and oak trees.
  • Fireblight is caused by a bacteria. The most typical symptom is branch die back from the tip down typically resembling a shepherd’s crook. Affected branches usually start dying in mid-May or June. Prune out dead branches about a foot below the dead tissue. Sterilize pruning shears between cuts. Plants susceptible: cotoneaster, pyracantha, apples, pears and Bradford pears.
  • Juniper Tip Blight is characterized by dead branch tips in juniper plantings. Two different fungi cause this blight. Small outbreaks can be pruned out. Fungicides are also an option. The timing of the treatments depends on the causal fungus. Blight caused by Phomopsis is treated in the spring. Blight caused by Kabatina is treated in the fall.
  • Oak Leaf Blister: The light green to yellow spots will turn dark brown or black later in the season. This disease is primarily cosmetic and requires no action.
  • Rose Rosette Disease (RRD): A disease believed to be caused by the recently identified Rose Rosette Virus, has been spreading through much of the wild rose population of the Midwestern, Southern, and Eastern United States for years. It has been confirmed in cultivated roses in Virginia and other states.
Virginia Cooperative Extension
Environment and Natural Resources
8033 Ashton Ave. Suite 105
Manassas VA 20109
Virginia Cooperative Extension complies with the Americans with Disabilities Act. If you are a person with a disability and require auxiliary aids services or other accommodations for a workshop or meeting please discuss your accommodation needs at least five days prior to the event with Virginia Cooperative Extension 703-792-6289/TDD PC 1-800-828-1120.


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