What Is A Photinia Leaf Spot?
A photinia leaf spot (PLS) is a common fungus infection of many species of plants including roses, azaleas, sunflowers, ragworts and other members of the Asteraceae family. It affects all parts of the plant but especially its leaves which are affected first. Leaves may turn brown or even black with necrotic spots. Some infected leaves die back completely while others remain green and wilt. Other symptoms include stunted growth, wilting and twig breakage.
Plants often have few symptoms at first, but if left untreated they will eventually succumb to the infection. The disease is not contagious so it cannot spread from one plant to another. It is caused by a type of fungus called Phytophthora ramorum.
The main symptom of PLS is that the leaves become discolored and then die back. The fungus causes the death of chlorophyll, which makes the plant unable to photosynthesize. When this happens, there is no oxygen available to make sugars for life and the plant dies.
What Is The Difference Between Photinia Leaf Spots And Other Plant Diseases?
The fungus that causes PLS is not the only pathogen out there that can affect plants. Many other diseases can harm plants to a greater or lesser extent, but the main difference is that these are caused by different types of fungi and bacteria.
BN (Botryosphaeria obtusa) affects a similar range of plant species. This type fungus is also common in warmer regions and causes similar symptoms. The disease is uncommon in the US, but it does occur in some areas like California and Southwestern regions of the country.
The main difference between PLS and BN is that the former is caused by a oomycete while the latter is a fungus. Both are fairly common types of plant disease in the United States. They can be spread by the same insects, namely snails and slugs.
How To Treat And Prevent
There are several treatments available to prevent and treat PLS infection. The most common treatment is for liquid applications that can be used on both outdoor and indoor plants. Some types of fungicides are available as dusts or dry flowable formulations. These may be more effective, but they may also damage plants if the concentration is too high.
If you decide on a liquid product, apply it to the foliage from early spring through early autumn. Apply it every seven to 14 days depending on the type of product that you have selected. There are few organic options such as Bio-Sphere and Serenade for preventative treatment.
There are several things that can help reduce the risk of infection too:
Keep your garden clean. Prune and remove any dead or diseased plant material.
Don’t plant new plants in areas that were previously diseased.
Keep an eye out for snails and slugs. These are a favored food of these mollusks and can easily spread disease from plant to plant.
Do not work in the garden when the foliage is wet.
When watering, do so early in the day so that plants have time to dry off before the night. The fungus that causes PLS is more likely to spread at night.
If you follow these guidelines, you can help prevent and reduce the risk of infection. Indeed, these same rules apply to all types of plant disease.
In general, the best way to protect your plants is to buy only healthy ones in the first place. Good garden centers will sell plants that are disease-free, and these can resist a lot of problems. Look for vibrant colors and plenty of foliage. Even if you follow all these guidelines though, you may still experience some problems with plant diseases.
This is part of what makes gardening fun (and sometimes frustrating).
What You Need To Know About PLS
In this guide, we’ve taken a close look at downy mildew on plants. These include the definition of the disease, what it looks like, how to identify it, the types of plants that it affects and how to treat and prevent it. While there are many different types of plant diseases out there, PLS is one of the most common.
Downy mildew can affect many types of garden plants. It’s common in the US, especially in warmer states. The fungus itself is very common and affects many different types of plants. There are several ways to treat downy mildew on plants, but the best way is to prevent it altogether by keeping your garden clean and applying a fungicide.
It’s important to keep your garden free of diseased plant material so that the fungus can’t spread.
Sources & references used in this article:
Entomosporium leaf spot control on Red-tip Photinia in the landscape by AK Hagan, JR Arkidge – Journal of Environmental …, 2011 – meridian.allenpress.com
Entomosporium Leaf Spot Control on Red-Tip Photinia with Drench and Foliar Fungicides in the Landscape by AK Hagan, JR Akridge – 2011 – aurora.auburn.edu
Efficacy of fungicides for control of Entomosporium leaf and berry spot of saskatoon by RM Lange, PS Bains, RJ Howard – Plant disease, 1998 – Am Phytopath Society
Photinia glabra: Red-Leaf Photinia1 by EF Gilman, DG Watson – researchgate.net
Diseases on vegetables and ornamentals 2011 by A Martinez – 2011 – athenaeum.libs.uga.edu