Each class as fountain warms into summer , verdant vegetables hold the attention of many an eager gardener . As raiser monitor their tomato flora , they may notice scattered jaundiced spying , a graying fore lesion , or a few branch wilt suspiciously . Concerned , they ask questions . What usually watch is a circling of opinion : “ Is this blight ? ” “ emphatically plague . ” “ good spray it for blight . ” “ possibly tomato blight ? ” And my personal favorite : “ It might be plague ! ”
On the one hand , I am thankful that many people are quick to point in the direction of a plant disease and its management , but too often these conversations end in more disarray . Simply put , tomato blight becomes the catch - all term for myriad pathogens and disorders that bear upon tomato . add up to the confusion is that there is no single pathogen known as tomato blight . There are in reality two very different disease : ahead of time blight and late blight of tomato .
What is early blight?
Usually seem each summer wherever tomatoes are grown , early blight is quite common . The disease is because of two species of fungus kingdom , Alternaria tomatophilaandAlternaria solani . The former is more virulent on tomato , while the latter also stimulate early blight on potato . Other solanaceous plants , including eggplant and nightshade weeds , may also show symptoms .
Alternariaspores overwinter on septic industrial plant debris left in the territory , or they arrive in the garden on infect seeds . The spore , call conida , pass around to lower stems and foliation by water splash , either from rain or irrigation . If the flora aerofoil remains wet for 5 to 10 hours , spores shoot to infect the industrial plant . The disease thrives in warm summer temperature , spreading best in the 75 ° to 85 ° F range . Since early blight need a retentive period of wetness , gamey humidness plays a cardinal function as well .
Symptoms admit circular brown lesions that start very small with a skirt yellow ring call a chlorotic annulus . blot grow up to half an inch in diam and often merge as leaves gradually chickenhearted and snuff it . These gray to brown lesions commonly take form a bull’s - heart pattern of rings as they spread out , a highly characteristic symptom . lesion also develop on petioles and stems , forming concentrical rings if they become large enough . When stem lesions look near the grease phone line on untried plants , the canker may encircle the whole stem , causing the entire plant to droop and die . When fruit is infect , black , sunken lesions strain next to the calyx ( top side ) .
septic lesions soon acquire spores of their own , open of go around farther by wind and rain . If you are straightaway to observe former blight , removing moved lower foliage and protect upper foliage with a fungicide can facilitate reduce further bed cover . It is important to jazz that symptom can be very unmanageable to key out from several other tomato diseases , especially Septoria leafage situation .
What is late blight?
It may come as a surprise to learn that late blight is one of the most notorious plant pathogens in history . You may know it by another name — potato late blight . Yes , this is the same being for the most part responsible for the great starvation in Ireland in the mid-1840s . primitively from Central America , late blight appear in the northeastern United States in 1843 , unfold wide over the next few years , and was carried to Belgium and Ireland , where it work havoc .
recently blight on tomatoes ( or potato ) is make by the organismPhytophthora infestans . It is not a lawful fungus but rather an oomycete , in a group of organisms call piss molds . The offending organism spread speedily in prolonged periods of cool , showery , humid weather . Uncommon in the home tomato garden , belated blight does show up sporadically each season , usually in Pennsylvania , New York , and surrounding states . confabulate the USABlight internet site ( usablight.org ) each year to learn if it has been cover in your area .
Initial symptoms of late blight are wilt petioles and large , blotchy , light green or water - soaked leaf lesions . tumid domain of stem tissue paper nigrify , and whole stems bug out to cave in . Infected tomatoes may reverse brown and leathery , with intragroup discoloration . In lactating weather condition , transmission produce a brightness , cottony white fungus . Under humid conditions , infected tissue paper produces spores that are easily move by nothingness , rain , or accidental human aid .
recent blight does not overwinter in the soil of frigid climates . It hold up on dead plant fabric , include infected , throw out tomato plant ; white potato tubers ; and other solanaceous plants . Thus , sanitation is critical . With confirmed late blight , allaffected plant life must be removed and demolish to prevent further spread . air samples to a diagnostic plantpathology clinic at a local university or alerting local extension agent will help monitor annual disease spread head .
Whether you are a new or seasoned Lycopersicon esculentum agriculturalist , keep in nous that a lot can go amiss with tomato plant harvest . However , tomato diversity allows for much flexibility . If early or later blight pestis your area , choose a resistive variety . If soil nematodes are a primal problem , attempt growing pot tomatoes . If late - time of year disease are a problem due to typical regional weather , try former maturing varieties . utilise the tool and resources uncommitted , and do n’t give up ! The year that climax in a delicious yield of juicy tomatoes will be deserving it .
|Science|
Best ways to combat tomato diseases
Matthew Borden , DPM , is a plant wellness consultant specializing in diagnostics andintegrated direction of landscape painting plant pests and disease .
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Keep a watchful eye out for early blight symptoms. This common disease spreads rapidly on leaves (left), petioles, and stems (above) and presents as yellowing tissue and brown lesions that expand to form target-like patterns.Photo left: Dr. Parthasarathy Seethapathy, Amrita School of Agricultural Sciences, Amrita Vishwa Vidyapeetham, Bugwood.org. Photo right: Robert Wick, University of Massachusetts, Bugwood.org
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Look to multiple parts of a plant to begin to diagnose diseases. The combination of collapsing shoots (above), blotchy leaf lesions (bottom left), and moldy or leathery fruit (bottom right) are key symptoms of late blight.Photos: courtesy of G. J. Holmes
