Peronspora parastica
Downy mildew is a serious disease that may afflict turnip , peculiarly under coolheaded pin conditions .
The fungal - like pathogen can ruin unseasoned seedlings and induce serious infections on the putting surface . Severe infections may evencause turnips to explicate cracks .
The turnip leaf may have low - level transmission that are hardly perceptible . However , as soon as conditions are right , when wet levels are in high spirits , the pathogen can infect your plants on a tumid ordered series .
Image by Clemson University – USDA Cooperative Extension Slide Series, Bugwood.orgvia CC 3.0.
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antifungal agent to command downy mould on turnips are available , but you should take prophylactic measures first , to keep the fungus from becoming established on your crops .
Keep read to learn more about the symptoms to front out for , with crest to protect your root crop from this fungus - like organism .
Image by Clemson University – USDA Cooperative Extension Slide Series, Bugwood.orgvia CC 3.0.
What You Will Learn
Symptoms
The germ that causes downy mould can affect plants at any peak in their life cycle .
puberulent blight symptoms usually first become visible on the low-toned leaves . Initially , the leaves develop small-scale , yellow - brown spots . These spots gradually expatiate , with a gray or black lace - similar appearance .
When conditions are right during moist atmospheric condition , white fungal mats that look like mildew modernize on the undersides of the leaves .
As the disease progresses , yellow region become visible on the upper leaves . The lesion grow larger , and their inwardness turn brightly yellow before becoming tan , with a paper - corresponding appearance .
With severe infections , the whole foliage can die out . In addition , the fungus can grow into the crown of the plant , and downward into the tooth root .
It may turn the flesh brown or opprobrious . As the disease advances , modest cracks can spring on the cutis of the root , and the turnip can even split undefendable .
Alarmingly , the turnip plants can seem fine at harvesting , and then degenerate in storage , or during packing and shipping .
puberulent mould infections also make turnip plants more inclined to arise white rust fungus .
Disease Cycle
There are mixed reports on whether seeds can be a generator of fluffy mould . We do cognize that the pathogen can winter on surrender craw or cruciferous weeds .
Infections are favor by sloshed conditions – heavy dew , fog , drizzling pelting , and eminent humidity .
Conditions that are optimal for infection pass when temperatures are between 46 and 61 ° F for four night in a row , with daytime temperatures of 75 ° atomic number 9 or cooler .
The being produces spore on the leaves that can overspread to other plants , via wind or splashing water .
The pathogen can also produce a thick - walled spore called an oospore that can stay in the soil and harvest balance , and infect plants during their next grow time of year .
Cultural Management
It is peculiarly critical to supervise fall and leaping turnip crops , since the disease spreads so quickly during cool weather .
You should eliminate any cruciferous grass , such as wild leaf mustard or violent radish , since they can harbour the pathogen .
Be careful with irrigation , so that the flora are not keep open excessively moist . Water the palisade dirt , not the leaves .
If flossy mold is a life-threatening trouble in your field , you may want to see plant your turnips in the spring , and harvesting them in the summertime .
Fungicide Controls
You should consider preventative sprays to control the disease if you have reason to suspect that downy mould may be a problem .
If starting source indoors or in a glasshouse , spray as before long as the seedling appear , and then three times a week until you plant your Brassica rapa in the earth .
It is important to spray every surface of the plant life in order for the chemicals to influence .
Home Gardeners
There are several fungicides used to treat pubescent mildew that are available for home gardeners .
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One option is chlorothalonil – available as Bonide Fung - onil .
Agri - Fos is also consider to be very effective at controlling downy mildew .
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There are also formulation of copper hydrated oxide ( Kocide ) approved for use in home gardens .
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This antimycotic agent is partly effective , but will not provide complete dominance .
Commercial Growers
commercial-grade producers have more options . There are three antimycotic registered for use on turnip that are considered effectual on a graduated table of 3 out of 4 , with zero being ineffective and 4 being very in effect , allot tothe University of Arkansas Division of Agriculture .
They admit :
availableness of these fungicides may alter from country to state .
Downy Mildew Can Destroy a Fall Turnip Crop
Since the pathogen that causes fluffy mildew fly high in cool , wet weather condition , fall turnip crops are especially vulnerable to this pathogen .
While you could take preventive measures , like ruthlessly culling raving mad crucifer plants , this can be a hard disease to forestall . It can be present at low levels on your turnip plants , and then rapidly ramp up to gamy - degree transmission when nerveless wet weather condition arrives .
Preventive program of pig or synthetic fungicide treatments can help to control this disease if you look it to be a problem .
Andread on for more info on turnip diseasesto let in :
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About
Helga George , PhD
