(Backyard Gardener - Photo Illustration - MetroCreativeConnection)

Hello Mid-Ohio Valley farmers and gardeners! Fall weather has finally arrived as daily temperatures are forecasted to peak in the mid-70s. Many backyard gardeners are harvesting tomatoes squash and sweet corn this week.

If you have a bunch of zucchini squash available from the garden, try one of our WVU Extension Healthy Recipes called baked-parmesan-squash. You can find this easy recipe video on our WVU Extension website.

Zucchini squash can also be cubed or shredded and frozen in Ziplocç bags. Plain zucchini is not suitable for canning because the high temperature in a pressure canner causes the watery squash to disintegrate. It is a low acid food and is not safe to can in a boiling water bath.

Zucchini contains large amounts of water. Freezing causes the water crystals to break down cell walls yielding a watery product when thawed and heated. As a result, frozen and thawed zucchini works best in products that are baked. Yes, zucchini bread this winter!

This week I want to talk about boxwoods and boxwood blight. Boxwoods (Buxus spp.) are one of the most popular shrubs in landscapes of West Virginia and are best known for their low maintenance, dense growth habit and deer resistance making them a favorite shrub for hedges It is not unlikely to find diverse cultivars of boxwoods belonging to many different species in the landscapes of the state.

Boxwoods are evergreen shrubs originally from Europe and Asia. They are one of the oldest known garden plants, dating back to 4000 BC. Today there are approximately 115 different cultivars and species commercially available for boxwoods to plant in the landscape.

Each species contributes unique characteristics, including size, color, insect resistance, and foliage. Common boxwood is a wide-spreading species with very dense, evergreen foliage and cold tolerance to about -50F. The leaves are dark green above and yellow-green below, reaching 1/2 to 1 1/2 inches in length, and are oblong to oval in shape.

Japanese boxwood is a low-growing, compact, heat-tolerant shrub with bright green leaves that are elliptical to lance-shaped, and reach 1/4 to 1″ in length. Korean boxwood is a loose, open-growing shrub that is very hardy, although the foliage may turn yellow to brown in the winter.

Boxwoods are easy to grow, require little maintenance, and are very tolerant of a range of soil types with optimal pH in the 5.5-7.2 range. They prefer partial or dappled shade but can tolerate full sun. Some varieties may experience bronzing of the foliage with sun overexposure, particularly in the winter.

Increased population and high-density landscape settings can result in certain diseases in boxwood, especially blight. It can be very destructive.

Boxwood blights are a fungal disease that can be fatal if no measures are taken to manage them at the early stage of infections when symptoms appear. There are two different fungal pathogens involved with blight with boxwood.

Volutella blight (Volutella buxi) infection turns boxwood leaves light green-yellow, transitioning to bronze, and finally become straw or yellow-tan in color. This fungal pathogen can also infect the stems, resulting in the yellowish loose or peeling bark.

Another fungal pathogen known as Calonectria blight (Calonectria pseudonaviculata) can also cause boxwood blight, which manifests as dark leaf spots that coalesce to form brown blotches. Calonectria affected boxwoods leaves drop off very quickly, giving the plant a barren appearance.

A key symptom that differentiates Calonectria blight from Volutella blight of boxwood is that narrow vertical black streaks (cankers) develop on green stems due to Calonectria infection, while Volutella infected stems show brown to black girdling streaks, followed by loosening of peeling of bark.

In moist conditions, boxwood infected with Volutella blight will have orange or salmon colored fungal fruiting structures called sporodochia. They will noticeable on the stems or underside of the leaves.

You can also take a few suspected leaves and put it inside a Ziplocç plastic bag with moist paper towel for 3-4 days to observe such growth. The undersides of infected leaves in case of Calonectria blight will mostly show white sporulation.

Both of these fungal pathogens can survive on infected plants or fallen leaves on the ground overwinter. The spores produced on infected leaves and stems during the growing season can be splash-dispersed through irrigation, rainfall, wind or pruning tools. This can spread the disease within a plant or to nearby boxwood shrubs.

Environmental stress such as drought, excessive water or winter injury can make boxwood plants more vulnerable to infections. The recent outbreak of Volutella blight in West Virginia and neighboring states may have a connection with the cold stress from arctic blast which occurred in December of last year.

While Volutella blight is present in the Mountain State and is considered an opportunistic pathogen that infects only stressed plants, Calonectria blight is more aggressive but incidence remains very low.

However, there is a potential for Calonectria infected plants to get in the area with new plants through the nursery trade. Homeowners and landscapers should make sure that infected plants are not purchased and planted.

If you have boxwood blight, take some steps to manage the disease. Prune out infected branches and destroy them by burning or hauling away in a trash bag. Pruning dense shrubs will also improve air movement, sunlight penetration and keep the canopy humidity low.

It is important to sanitize pruning tools by dipping them in a 10% bleach solution or 70% ethyl alcohol between each cut. Do not prune when foliage is wet. If possible, remove the infected fallen leaves and litters.

Boxwoods are susceptible to drought, so alleviate plant stress by providing irrigation as needed. It is recommended to irrigate through drip irrigation and avoid overhead sprinklers to keep foliage dry.

Do not use horticultural fabric as a mulch to suppress weed growth. It is better to use bark or compost mulch that may help in holding moisture and promoting root growth.

American, English, and Korean boxwoods are all susceptible to blight, although disease severity varies among cultivars. For example, boxwood cultivars “Green Velvet,” “Green Mound,” “Green Mountain” and “Pincushion” have some resistance against Volutella blight compared to highly susceptible cultivar “Green Gem.”

Similarly, cultivars “Golden Dream,” “Green Beauty” and “National” are resistant but “Suffruiticosa,” “Arborescens” and “Justin Brouwers” are highly susceptible to Calonectria blight.

Chemical control of these two diseases is also a little different, so it is very critical to identify the disease accurately. If you suspect boxwood blight, send samples of the suspected plant to the WVU Plant Diagnostic Clinic.

A combination of chlorothalonil (Bravoç, Daconiçl, Fungonil ç) and thiphanate methyl (Cleary 3336) can provide good control of Volutella blight if used preventatively or at the very early stage of symptom expression.

Removal of highly infected stems by pruning before fungicide application can improve the efficacy of the products. Other products that are registered for the control of Volutella blight include propiconazole, copper and mancozeb. For preventing Calonectria blight, Heritageç, Medallionç, Muralç,and Palladiumç can be used in alternation with Daconilç.

Contact me at the Wood County WVU Extension Office 304-424-1960 or e-mail me at jj.barrett@mail.wvu.edu with questions. Until next time, Good Luck and Happy Gardening!