Order Verbena at the our store-Shop Look for white, dusty patches on the leaves. A caller rang in and asked what to do about mildew on her Verbena bonariensis. Verbena plants are generally hardy against disease, but if you've had a wet summer, you may need to remove any growth with powdery mildew. Once the disease becomes established, it is highly difficult to eradicate it. In my region, Verbena bonariensis is a perennial rather than an annual. It is most familiar as a disease of cucurbits, the group of vegetables that includes cucumbers, squash and pumpkins. P.O. All rights reserved. June 2019 in Problem solving. It’s unlikely you can meet the watering or nutrient needs of plants in pots long-term – you’ll either undo or overdo it. Powdery mildew on verbena typically begins as thin, whitish patches on the underside of lower leaves. This means that increasing air circulation and reducing moisture are key to getting this disease under control. Leaves with this appearance should be turned over to check for PM underneath. This ability of PM to be unobtrusive until temperature and humidity conditions trigger dramatic spread is the reason why monitoring your crop is so critical. PDF: Pests & Diseases: Verbenas & Powdery Mildew, Culture Report: Begonia Double Delight Series. This plant often contracts powdery mildew, especially in humid summers. Rainbowfish Posts: 276. Charlotte 987 Posts: 7. Liked it? Lower leaves generally are the first to show symptoms and later become necrotic. Yet, there is one pathogen group that takes advantage of perfectly healthy plants, those that are not stressed in any way: the powdery mildews (PM). Maybe I should switch to the native. On my garden patrol this morning I spotted some powdery mildew on a couple of my new Verbena bonariensis plants. Verbena bonariensis is an annual up here in the New England, but reseeds easily so you only need to start with one plant to gain many over a short period of time. I’m wondering whether this is a result of over watering. Water tall verbena regularly during the first growing season. Verbenas are annual or perennial plants with purple, pink, red or white flowers. Ironweed is of the aster family. It's getting quite tall, with some close to 8 feet even though it's not supposed to top 6 feet, and in the wind has taken a battering so that I've had to stake some of the bushes which were blown over. This outstanding annual or perennial deserves its popularity. See: Greenhouse Plants, Ornamental-Powdery Mildew. The lower … Although PM is obvious when it is well established, it can reside in small colonies on the undersurfaces of leaves that are not detectable until conditions allow the development of an epidemic that magnifies the visible signs of the disease. Plant tall verbena seeds directly in the garden, in moist, well-drained soil. Powdery mildew is a relatively common fungus that many plants can contract. ... Julia, some years my VB get powdery mildew, though not always. Verbena bonariensis with powdery mildew. V. bonariensis is commonly grown from seed which germinates readily without pre-treatment, but can … Because PM caused by Podosphaera xanthii has been especially troublesome to manage on verbena in recent years, we have focused on it in an American Floral Endowment-funded research project that aims to improve PM management for ornamentals. © 2020 Great American Media Services & Greenhouse Product News. Botrytis blight often occurs under overly moist conditions. I’m wondering whether this is a result of over watering. The fungus Alternaria causes small water-soaked spots on the lower, older leaves of Verbenas. These plants have square stems and bear small flowers in a wide variety of arrangements. Look for white, dusty patches on the leaves. Some varieties of Verbena are resistant to powdery mildew, such as the Aztec, Laskar and Tukana series. I have used a fungicide spray (Daconil (chlorotholonil) two bottles so far) and I am not noticing that it looks to be improving or going away. They should either scout these cultivars very carefully for the first symptoms, paying attention to the undersides of lower leaves, or consider using fungicides preventively. It has few insect or disease problems other than powdery mildew. Verbena plants are generally hardy against disease, but if you've had a wet summer, you may need to remove any growth with powdery mildew.