Powdery mildew is a fungal disease that results in a powdery gray or white coating on the leaves and stems of infected plants. Photo: N. P. Goldberg, New Mexico State University. Powdery mildew afflicts many plants: crape myrtle, rose, verbena, phlox and euonymus, to name a few. For my sins, I was listening to my local radio gardening phone-in on Sunday. Hence the fact the verbenas in question were stressed out and riddled with powdery mildew. It’s a big attractant of butterflies and bees. I'll try Verbena bonariensis 'Lollipop' in a sunnier location. If I Could Only Grow One Annual Next Year, It Would Be…. There are even some plants, such as the lilac, that can have the powdery mildew on it and it doesn’t hurt the plant that much.So using a homemade cure for powdery mildew on the hardier plants isn’t necessary. This is a wonderful plant for bringing height to the border and its … Although powdery mildew diseases are generally very host-specific, attacking only very closely related plants, the verbena disease is an exception in that it is the same powdery mildew that affects squash and cucumber (Fig 20. Powdery mildew is sometimes confused with the similar downy mildew. Can I avoid this in the future by making sure they get a bit more water than this year? In contrast, powdery mildew will appear anywhere on the leaf. yellow to light green, irregular leaf lesions that may become purple to dark brown All without the need for nasty fungicides (if you want to find out why using fungicides is bad for invertebrates, you might like to listen to my episode on Worms here). But never mind verbenas in pots, Verbena bonariensis in the garden often has powdery mildew at the end of the year too. This symptom could also be confused with nitrogen deficiency. The main drivers of powdery mildew are temperature and moisture. Some cultivars of annual verbena are less susceptible to powdery mildew … All Rights Reserved. The lower leaves generally are the first to show symptoms. UC ANR Publication 7493, at http://ipm.ucanr.edu/PMG/PESTNOTES/pn7493.html. Liked it? Powdery mildew appears as a white powder fungus on the surfaces of leaves. hello@rootsandall.co.uk I now better understand why a handful of my plants are getting this disease two years in a row. So if, like Marjory in Cooden Beach (the names have been changed to protect the innocent), you have powdery mildew on your Verbena bonariensis, first ignore your radio. The fungus usually attacks the leaves of a plant when nights are cool but daytime temperatures are warm. Bonariensis Verbena. Leaves, stems and buds grow distorted as the disease progresses and the plant becomes distorted. Colonization is generally on the leaf underside. The latest windstorm completely flattened my verbena so it has made the difficult decision to remove the plant much easier. It most often infects verbena that does not receive enough sunlight, or is under stress from severe drought or other causes. Powdery Mildew: White fungal growth forms on the upper surface of leaves and may form on flower petals. However, downy mildew appears only on the bottom (or underside) of the leaf. Despite different water year types over the past few years, the mildew persists, so I'm now trying different cultivars and locations. Powdery mildew fungi are highly specialized in that different fungi cause disease on different plants, with fungi favoring plants in the same family or only one species of plant. *Efficacy on Powdery Mildew (Podosphaera xanthii) on Verbena (Verbena x hybrida) ‘Obsession Lilac’, Hausbeck, MI, 2005, Experiment 1. ..... 67 Table 83. Of course it provided plenty of seedlings, so I replaced it with one of those. Symptoms Colonies appear as the typical powdery, white patches on leaf surfaces. Your email address will not be published. If left untreated, the patches join together and cover entire leaves. The leaves turn yellow, become necrotic and fall off. Plants want to be in the ground. Take note that downy mildew isn’t as powdery in appearance, either. Thank you for a well written article that addressed powdery mildew on verbena specifically, as well as under which general conditions this mildew thrives. It has tall, architectural stems with sparse leaves, crowned by flattish heads of lavender-purple flowers. Pythium Root Rot: Roots are dark brown. I tried to research verbena cultivars that are more resistant to powdery mildew but only found options for the groundcover varieties of the plant, as opposed to the taller variety that I prefer. You are currently not signed in. Thank you for the information and suggestions! http://ipm.ucanr.edu/PMG/PESTNOTES/pn7493.html. A caller rang in and asked what to do about mildew on her Verbena bonariensis. Verbena hybrids developed by Proven Winners® to be more robust, more mildew resistant, and more resilient than older varieties. It’s unlikely you can meet the watering or nutrient needs of plants in pots long-term – you’ll either undo or overdo it. If it’s growing happily somewhere, chances are it’s water-stressed because verbenas are only truly happy where they’re hard up for water. Agriculture and Natural Resources, University of California. A.Powdery mildew is a fungal disease that is difficult to avoid when conditions are favorable for it.