If you ’re growing pumpkin in your garden , you may have seen blanched spots come out on the leave and vine .
What ’s up with that ? It ’s potential that your plants are infected with a fungous disease yell powdery mildew .
This disease is very vernacular and in many casescan be treat successfully . However , if it is allowed to spread , in severe cases the plants may drop their leave and debunk the fruit to sunscald .
We link to vender to help you find relevant products . If you buy from one of our links , we may earn a mission .
In addition , the educate yield may be stunt and fail to mature properly .
Flower bud can also be infected which will prevent them from opening and they ’ll dry out and fall off the plant .
As Dr. Dan Egel posit in a Purdue University Vegetable Crops Hotline article onPumpkin Disease Management Steps , it is “ well-nigh impossible to find a pumpkin vine in August without powdery mildew . ”
However , with a little right planning and diligent care , this does not have to be the case !
Read on to learn how to preclude and treat powdery mildew on your pumpkin plants .
Here ’s what I will overlay :
What You’ll Learn
What Is Powdery Mildew?
Powdery mould is a very mutual works disease because of hundreds of different species of fungi .
While the infection does n’t typically kill mature pumpkin plant , it can induce problem in the develop fruit , and can make stunted growth in vernal plants .
The name is descend from the typical symptoms that first appear as ashen position on the leaves and grow into a grayish - white powdery substance covering the foliage .
This “ mould ” lie of a compounding of fungal spores and threads known as mycelia .
In pumpkins – and cucumbers , crush , melons , and cosmetic gourds – this disease is primarily caused byPodosphaera xanthii(formerly known asSphaerotheca fulginea ) .
In moderate regions , pumpkin plant typically start showing symptom in the summertime when the plants come out to grow fruit .
However , severe infections can occur earlier in the time of year that can cause bud drop and stunted vine development .
The symptoms start with the appearance of white spots on the bottom of the leave of absence , which can well go unnoticed . The fungus can spread to wrap up the intact leaf , which finally turn chicken , and then dark brown in severe cases .
When this happens , the leaf decrease off , and the exposed pumpkins can be scalded by the sun , ripen poorly , and grow to be much smaller than require .
Conditions That Favor Infection
Unlike most fungus that proliferate in moist , damp conditions , powdery mold can taint plants in ironic shape , as long as there is enough humidity to turn on the spores to overspread .
Free pee actuallyinhibitsthe germination of these spores .
This mean that your pumpkin plants are at hazard disregarding of whether you live in a dry or a moist clime .
These fungi are most probable to infect your plant when it ’s hot and teetotal during the day and nerveless and humid at night . Daytime temperatures of 68 to 81 ° F are ideal for contagion , however if temperature rise above 100 ° F , the fungus will no longer be active .
heavy leaf on the vines increase the plants ’ susceptibleness to this disease , as the want of airflow can cause the infection to spread rapidly .
Additionally , plants that are push by Mary Jane or uprise in shady locations create idealistic precondition for the bed covering of powdery mold .
Lush plants that have been over - fertilized with nitrogen are also more susceptible to infection . The fungus infect new growth , induce it to be stunted .
Bush variety show that grow in a more compact form can also be taint if the dense plant canopy increases the amount of moisture in the shopping mall of the plant , result in the high-pitched humidity that favors the evolution of powdery mildew .
Inspect Your Plants Weekly
Since this is such a common and in some cases potentially serious disease , you should inspect your works on a regular basis . This will help you to take whole step to preclude an infection from propagate and damaging your crop .
Check the bottom of the old parting first , since that ’s where these infections run to originate .
Michelle Grabowski , Extension Educator for the University of Minnesota , recommendschecking at least five mature leaves per plant each weekto ensure they are not infect .
Begin by checking the vine and downhearted surface of the leaf for wan yellow situation that quickly boom to white thin ribbon - like hoi polloi .
Do n’t forget to check into the cap of the plant life and the vines , too .
Make Sure It’s Not Downy Mildew
One complication when diagnosing an outbreak of powdery mildew is that there is another pathogen that can snipe pumpkins that also produces off-white spots : fluffy mildew .
While it act like a fungus , the pathogen that causes pubescent mildew is an exclusively different organism – a piddle mould or oomycete .
This mean that wholly unlike technique for control are used for the two pathogen . Fungicides that work on puberulent mold are ineffective on powdery mildew , and frailty versa .
you may tell if your pumpkin vine are infected with downy mold , because there will be xanthous spots on the upper surface of the leave and purpurate to gray spots on the bottom of the leaves .
In dividing line , powdery mildew results in white muscae volitantes on the bottom of the leaves .
Another way to secern the two infections asunder is that the downy mildew spots are angulate . They break off growing at the veins , so they calculate like a patchwork . you could see this most clearly on the bottom of the leaves .
you’re able to learn more about how to treat fluffy mold in our templet to common pumpkin vine disease . ( coming soon ! )
Treatment Options
If you recover sign of a powdery mildew infection , you need to take action mechanism instantly to prevent it from spreading . A mild face of powdery mould can become more severe if left untreated .
A severe infection can induce your fruit to have less flavor , computer storage poorly , get scalded by the Sunday , and ripen incompletely . In the worst example , the infection can pass over out your entire craw .
And whatever intervention you choose , be sure to go for it to both the tops and the bottom of the leave of absence and all of the vine .
Remove the Fungus
Your first step should be to transfer the most severely infected leaves and vines . leafage that has bulge to yellow or sprain brown , or leaves that are totally covered with the powdery coating can be trimmed , but those that are only partially coated can be treated as distinguish below .
Also absent any debris around the plant , and even discard anymulchyou may have applied . This is a good time to cautiously move out any weeds or volunteer plants in the straightaway vicinity .
Remember to sterilize your tools before and after use , so they wo n’t spread the infection to other cucurbit . you’re able to habituate either 10 percent blanching agent or 70 percent rubbing alcohol .
And wash off your mitt with soap and water once you are done .
Organic and Home Remedies
There are home therapeutic , such as Milk River , that you could spray on your pumpkin plant . Mix equal amounts of Milk River and water and spray the tops and undersides of the leaves twice a week .
Mil - Stop Foliar Spray
One option that is certified organic is the atomic number 19 dicarbonate sprayer Mil - Stop that isavailable from Arbico Organics .
Sulfur is another constituent compound that can be highly effective against powdery mildew on pumpkin if used before the infection becomes too established .
Bonide Sulfur Plant Fungicide
you could find out Bonide Sulfur Plant Fungicide alsoavailable from Arbico Organics .
This product is in powder figure and can be applied as a dust or ruffle with water and used as a spray .
Biofungicides are also ofttimes effective against this disease .
take about these treatments and more in ourguide to constitutive and home curative treatments for powdery mildew .
Conventional Fungicides
The fungi that cause powdery mould are highly effectual at developingresistance to fungicides , so chemicals that formerly controlled the disease can frequently become ineffective .
For this reason , experts powerfully recommend alternating two fungicides with dissimilar modes of action ( FRAC code ) as frequently as every 10 days to facilitate prevent this from happening . Or even using two different antimycotic agent simultaneously .
run on Cucurbita pepo and other cucurbits cover in the 2020 version of theMidwest Vegetable Production Guideidentified the following antifungal that provide effective mastery of powdery mould :
If you opt to go this treatment route , apply fungicides at the first sign of transmission , and always watch over the directions on the recording label .
Keep in idea that some chemical fungicide can affect pollinators , so if potential , prison term your applications for when there are fewer pollinators active in your garden .
Learn more about thesafe employment of chemicals in your garden in this guide .
Prevention
There are whole step you’re able to take to limit the susceptibleness of your plant to the depredation of powdery mildew .
These include proficient gardening practices such as provide adequate spacing between plants , prune your pumpkin vine vinesto admit for air flow , irrigating at the base of plant instead of on the leaf , and planting immune varieties .
Cultural Controls
When you are planning your pumpkin vine eyepatch , there are a number of expert practice to keep in thinker , all of which are covered in ourguide to growing pumpkins .
To recap : make certain you implant them in full sunshine , and space the industrial plant far enough apart that they wo n’t grow over each other . Ideally , the hills should be six to eight groundwork aside to allow for the vines to spread .
If you lack infinite in your garden , you could considertraining the vines up a trellis to grow them vertically .
Keep the expanse around your plants gratis from skunk and garden debris .
Plants that are stressed from inadequate or unconventional care such as under- or overwatering will be more susceptible to transmission .
Do Not Overfertilize
The last affair you want is a lot of lush , leafy immature ontogeny on your pumpkin vines that will make them more susceptible to powdery mildew .
Test your soilbefore planting to get a salutary idea of the alimental balance before you apply any fertilizer or other amendment .
Be peculiarly careful not to fertilise with too much nitrogen , particularly after the plant has started to flower .
Learn and when to fertilise pumpkin vine in this guide .
Plant Resistant Varieties
There are variety show available that have been shown to exhibit resistivity to powdery mildew include :
Keep in thinker that when you see the Christian Bible resistant , this does not intend that the industrial plant areimmuneto the disease .
If the conditions are correct , even resistant plants can become taint with powdery mould .
The reward of growing resistant varieties is that plants are less potential to become infected early in the time of year and you may normally fend off a serious contagion .
Mature plants , infected later in the season are easier to care for successfully .
A Note on Crop Rotation
Good gardening practice recommends rotating away from pumpkins and other cucurbits for two yr to aid preclude the bed cover of pesterer and disease .
In the case of powdery mildew , this is not always effective .
In some locations , the fungus may remain dormant in the soil , quick to spring into action with the arriver of the correct circumstance .
However , some experts observe that infections do notnormallystart from the remains of the fungi overwintering in your garden and that windblown spores are usually the basal seed of transmission .
nurseryman in more temperate climates are less likely to have to worry about the kingdom Fungi overwintering in their garden .
Keep the Ravages of Powdery Mildew at Bay
While pumpkin plants frequently contract powdery mildew , if you are diligent you could help them continue to produce healthy yield .
Planting tolerant varieties , spacing them properly at planting time , and clip your vines will help to prevent the disease from call for handle .
Checking your plants ofttimes will help oneself you protrude treatment early if they do become infected .
Fortunately , there are a diversity of constituent and ceremonious chemical discussion for powdery mould on pumpkins .
And for more info aboutgrowing pumpkinsin your garden , check out these guides next :
© Ask the Experts , LLC . ALL right RESERVED.See our TOSfor more details . Cartesian product photos via Arbico Organics . Uncredited photos : Shutterstock .
About
Helga George , PhD
