Don’t Let Downey Mildew Get You Down!

DMR 401 Slicing Cucumber

A few weeks ago we asked our Facebook followers what their biggest gardening challenge is. While there were a variety of answers (and we hope to address many of them here on the blog), one common one we’d like to start with is downy mildew.

It may look like a fungus but downy mildew is actually a parasitic organism closely related to algae that can affect a variety of plants including basil, lettuce, spinach, melons, cucumbers, and squash. It causes pale green and yellow spots to form on the upper surface of the leaves. Spots of blueish or white fuzz may also form on the underside. As it progresses the leaves will turn brown and fall off. It rarely kills the entire plant but can cause a significant reduction in crop yields.

Unfortunately, there aren’t many organic methods available to treat downy mildew. Some studies and anecdotal evidence suggest that copper or neem oil may help in some cases but they both seem to be far from reliable. Instead, we’ll discuss ways to prevent downy mildew in the first place.

Use trellises.

Downey mildew loves moist conditions so providing your plants with good airflow is an excellent way to prevent the disease. Getting vining plants up off the ground is a great way to accomplish this. Many cucurbits can be grown on a trellis.

Vertical Gardening: The Beginners Guide to Trellising Plants

Water carefully.

Another way to prevent downy mildew by controlling moisture is to water with care. This means watering in the morning so the plants can dry throughout the day and/or using drip irrigation or soaker hoses rather than overhead watering.

Prune your plants.

If appropriate, prune your plants to increase air circulation.

Space your plants properly.

While it’s sometimes okay to space plants closely together if you struggle with downy mildew, give them room. Following spacing instructions is another way you can increase airflow around your plants and avoid moisture. It also helps ensure your plants have adequate nutrition and are less susceptible to disease.

Be vigilant.

Downey mildew can spread from plant to plant so diseased individuals should be removed as soon as you notice them.

Try disease-resistant varieties.

While there are many different strains of downy mildew there are some downy mildew resistant varieties. We carry DMR 401 cucumbers from Michael Mazourek’s breeding program at Cornell University that offer good resistance and excellent flavor.

Choose short season varieties.

Due to the fact that downy mildew thrives in humid conditions, you may be able to avoid it by growing short-season varieties and avoiding the bulk of the wet weather in fall and spring. Short season watermelons like Blacktail Mountain and winter squash like Burpee’s Butterbush or Table Queen are great choices.  


Unfortunately, there is no organic cure-all for downy mildew. However, following these tips can help you keep it from wreaking havoc on your garden.


AHS Honors Ira Wallace with Paul Ecke Jr. Commercial Award

Alexandria, VA (March 19, 2019). Ira Wallace, co-owner of Southern Exposure Seed Exchange (SESE), has been named the 2019 recipient of the American Horticultural Society’s (AHS) Paul Ecke Jr. Commercial Award, which is awarded to an individual or company whose commitment to the highest standards of excellence in the field of commercial horticulture contributes to the betterment of gardening practices everywhere 

The award is one of the Great American Gardeners Awards that the AHS presents annually to individuals, organizations, and businesses that represent the best in American gardening. Each of the recipients has contributed significantly to fields such as scientific research, garden communication, landscape design, youth gardening, and conservation.

A passionate proponent of heirloom and open pollinated seeds, Wallace cooperatively manages SESE with other members of the Acorn Community Farm in Mineral, Virginia. She has been instrumental in growing SESE into a successful supplier of more than 700 varieties of seeds that are carefully selected for superior flavor and performance in the Southeast and Mid-Atlantic. 

With SESE as a successful model, Wallace advocates for democratizing the seed supply and providing broader access to healthy, flavorful food. She cofounded the annual Heritage Harvest Festival in 2007 at Thomas Jefferson’s Monticello estate, which exposes thousands of visitors to heirloom plants and promotes their preservation. She also works on a global scale through partnerships with Seed Programs International, providing seeds and education to impoverished farmers abroad. She is the author of The Timber Press Guide to Vegetable Gardening in the Southeast (2013), and a board member of the Organic Seed Alliance. 

On Friday, June 21, 2019, the AHS will honor Wallace and the other award recipients during the Great American Gardeners Awards Ceremony and Banquet, held at the Society’s River Farm headquarters in Alexandria, Virginia. For full descriptions of each award and brief biographies of this year’s recipients, please visit our 2019 Award Winners.

About the American Horticultural Society

The American Horticultural Society, founded in 1922, is an educational, nonprofit, 501(c)(3) organization that recognizes and promotes excellence in American horticulture. One of the oldest and most prestigious gardening organizations, AHS is dedicated to making America a nation of gardeners, a land of gardens. Its mission is to open the eyes of all Americans to the vital connection between people and plants, to inspire all Americans to become responsible caretakers of the Earth, to celebrate America’s diversity through the art and science of horticulture, and to lead this effort by sharing the Society’s unique national resources with all Americans.

*The above is a copy of the AHS press release.

5 Butterflies Found in the Mid-Atlantic & What to Plant for Them

By now many have heard about and understand the plight of the Monarch butterfly. Over the last few decades, their numbers have been steadily declining as they face food and habitat loss as well as pesticide exposure. Though they’re certainly a deserving and beloved species (plant milkweed!), Monarchs aren’t the only insect or even butterfly that’s struggling. Here are five slightly lesser known butterflies found in the Mid-Atlantic and what you can plant this year to help them.

Photograph of an American Copper from Mass Audubon

American Copper Lycaena phlaeas americana

The American Copper’s is a fairly common butterfly though anecdotally it is seen less frequently today than in the past. These butterflies are orange and grey with black spots.

American Copper caterpillars preferred larval host plant (the plant where a butterfly lays eggs and is eaten by caterpillars) is Sheep Sorrel though it will use curly dock. Leaving sheep sorrel and curly dock available is important for their survival. As adults American Copper butterflies will feed on a wide variety of available flowers.   

Photograph of a Black Swallowtail from Mass Audubon

Black Swallowtail Papilio polyxenes

Commonly mistaken for other swallowtails this mostly black butterfly can be distinguished from other species by the black center on the orange spot on the inside corner of their hindwing. 

If you love the black swallowtail you may have to be willing to share a few of your crops. Black Swallowtail caterpillars will feed on carrots, dill, fennel, and parsley. As adults black swallowtails will feed on a variety of flowers. Like many other butterflies, they are particularly attracted to species such as milkweed, thistle, and clovers.

Photograph of a Common Sootywing from Mass Audubon

Common Sootywing Pholisora catullus

This butterfly can be identified by its glossy black (sometimes dark brown) appearance and the double rows of white dots prominent on the outer margins of the upper forewings. 

The Sootywing’s favorite host plants are lambsquarters, amaranth, and cockscomb (celosia). Adding some of these to your garden or in the case of lambs quarters simply letting them grow can help this butterfly thrive in your yard. Adult Common Sootywings can be found feeding on dogbane, common milkweed, purple loosestrife, and wild indigo. 

Photograph of a Long-tailed Skipper from Mass Audubon

Long-tailed Skipper Urbanus proteus

The Long-tailed Skipper gets its name from the long tails on its hindwings. It can also be identified by its iridescent blue-green head, thorax, and basal areas of both wings. 

This species of caterpillars feed on legumes, including cultivated varieties. Legumes include all sorts of beans and peas, alfalfa, clovers, and wisteria. Many of these species also happen to be really easy to grow. In their butterfly stage, they will feed on a variety of flowers. 

Photograph of an Orange Sulfur from Mass Audubon

Orange Sulfur Colias eurytheme

The Orange Sulfur can be identified by yellow-orange to darker orange upper wing surfaces.

Like the Long-tailed Skipper, Orange Sulfur Caterpillars feed on legumes. However, Orange Sulfurs have a strong preference for alfalfa earning them their nickname the alfalfa butterfly. As adults, they aren’t selective about which type of flowers they feed on.

Additional Tips

A few great flowers for many butterflies include:

The most important consideration with flowers is providing blooms throughout the season. Plant successions and choose flowers with a variety of bloom times from early to late. Choosing native plant varieties can also help butterflies succeed.  Check out our Welcome-to-the-Garden Pollinator Collection.

Avoid the use of pesticides whenever possible. Even certified organic pesticides can affect more than the targeted species. Especially if you live in a dry area consider adding a water feature for butterflies and other pollinators to drink from. 

These are just a small fraction of the Mid-Atlantic’s native butterflies. If you’d like to help butterflies and other pollinators consider some of these tips as your planning and working in your garden this season. 

Saving the Past for the Future