The three misunderstandings about this common condition
Powdery mildews may be the plant disease most recognizable to nurseryman . They are knownfor the gray to white patches of cold fungalgrowth that develop on leaf of numerous plantspecies . Over the old age , however , I have noticed that powdery mildews are also one of the mostmisunderstood vernacular garden disease . A close look at these diseases should avail you good handle them when they inevitably show up .
1. There isn’t just one kind
The first thing nurseryman misunderstand is that powdery mildew are not a exclusive fungal organism that , if left untreated , will spread across the garden , jumping from plant to implant in an unstoppable wave of moth-eaten harm . Instead , they are because of legion coinage of powdery mildew fungi , most of which are relatively host - specific and may only taint a single plant life , genus , or family , with great variation in susceptibleness therein .
The symptoms can be just as varied . Powdery mildews are best known for causing circular white patches on leaves ; however , it is important to know that symptoms diverge due to the many species and boniface plants affected . But some infections may look as little more than a lightheaded dusting across badly color new increment , as scabby or rustlike patch on leave and stems , and sometimes as reddish or violet discoloration and tell apart that may lack blank powdery growth . Usually , impact leaves of herbaceous perennials will yellow and drop prematurely , while more serious infections on woody plants may result in more lasting withering and distortion of shoots . However , plants are very rarely killed by powdery mildews .
100 of powdery mildew metal money may be present in your region , with perhaps a few dozen make usual garden powdery mildew transmission on their specific host plant groups . So when diverseplant grouping in your garden are being feign simultaneously by dissimilar powdery mold species , you know that environmental conditions are generally favoring powdery mildew exploitation , which you could at least part alleviate .
2. It’s not about wet leaves
A 2nd misunderstanding about powdery mildewsis that they are have by the same condition that apply to most other common fungal and bacterial leaf spots and rusts . Most fungal and bacterial diseases are favored by warm weather , eminent humidity , and freestanding water on the leaf or flora surface . This is not the case with powdery mildews , which prefer the quick days , gamey proportional humidity , and nerveless Nox of spring and fall for infect plant tissues . Wet foliage are not necessary , and water on the leafage actually subdue powdery mould contagion .
In another departure from most other foliar disease , powdery mildews flourish in the tender , dry weather of summer . This is because infection that were established in spring get to release millions of diminutive summertime spores , address conidia , that float on the breeze and need only a bit of high-pitched comparative humidness to germinate and infect new plant tissue .
My favorite way powdery mould are different is that they are among the few fungal disease you might come up activeduring winter andearly spring . An authoritative one to watch for is sight powdery mildew , which is often seen on sess such as Lamium amplexicaule and idle nettle . The powdery mildew species infect them ( Neoerysiphe galeopsidis ) has a full master of ceremonies range and is capable of spreading to many other mint family plants in your garden by and by in saltation , as well as to a few herbaceous shrubs from other families .
3. It’s not untreatable
A third misunderstanding is that powdery mildew are difficult or even impossible to treat . They may be difficult to eradicate entirely , but we have many undecomposed direction options . Remember , though , that infections occur recently in the time of year are unlikely to make any significant harm , and no treatment may be required beyond sanitation . If you do need to take action , here are some idea .
Matthew Borden , DPM , is a plant health advisor specializing in diagnostics andintegrated direction of landscape plant pests and diseases .
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It’s not usually this bad. Powdery mildew can cause severe distortion, but only in extreme cases.Photo: courtesy of Matthew Borden
Just another reason to weed. Powdery mildews can overwinter on common weeds and infect ornamental plants later in the growing season.Photo: courtesy of Matthew Borden
Photo: courtesy of Matthew Borden
