helianthus , Helianthus annuus , are annual in the Asteraceae sept desirable for cultivation in Zones 2 to 11 .
Whether you develop them for their ornamental value or the edible seeds , these flowers are a bright and sunny accession to your summer garden .
When leave with optimum growing condition , these beautiful and vivacious flowers are n’t prone to many plant life diseases , but you ’ll call for to know what to look for if pathogens do make out to chatter .
Photo credit: Thirunarayanan Perumal, Banaras Hindu University, Bugwood.org
Inour guide to growing sunflower , we cover how to plant and care forHelianthus .
Whether you ’re arise cute littleteddy bear typesorblack rock oil sunflowersfor the birds , this article will hash out seven common diseases that can ruin the flowered display .
Here ’s the lineup :
Photo credit: Thirunarayanan Perumal, Banaras Hindu University, Bugwood.org
7 Common Sunflower Diseases
1 . Alternaria Leaf Blight
2 . Downy Mildew
3 . Phoma Black Stem
4 . Phomopsis Stem Canker
5 . Powdery Mildew
6 . rusting
7 . Septoria Leaf Spot
get by the fungal speciesAlternaria helianthiorA. zinniae , Alternaria leaf blight is most potential to appear in quick , humid conditions , particularly after rain as wet is a prime number one wood of disease development .
Infected specimens will exhibit small , dark , sometimes chicken - ring spot on the leaf , typically along the margins or towards the leaf tips .
The spots will eventually blend and develop in sizing , eventually covering the bulk of a leaf . In time , infected specimens will miss their leaves – generally the low-toned leave-taking first – and finally die .
The pathogens can distribute via wind or splashing water , be seedborne , survive in weed host , and overwinter in craw rubble or the soil . And even if an infected helianthus does n’t fail , having blighted leaf wo n’t help it to develop the lovely blooms .
Maintaining appropriate spacing to elevate tolerable air circulation , pruning symptomatic foliage , and watering at soil level can help curb the ranch .
If a majority of your works are infected , you ’ll want to rend them up and put away of them in the trumpery , not on the compost spate .
If you’regrowing sunflower as a blanket harvest , in the case of contagion verify you rotate your crops and do n’t plantHelianthusin the same spot for two to three old age .
Many specie can hurt from a variety show of unlike type of mould , but this flavor of pubescent mildew – induce by the fungusPlasmopara halstedi – is actually unique toHelianthus .
Capable of surviving in soil for up to a decade , P. halstedithrives in cool temperature , gamey humidness , and waterlogged conditions .
If these conditions are present during seed germination and seedling growth , young specimen become infected and commonly die apace .
If these juveniles make it to adulthood , they ’ll lack vim and typically exhibit chlorotic leaves with white cottony outgrowth on the undersides . If septic works do n’t fail , they ’ll suffer from stunted emergence and reduced ejaculate readiness .
Growing resistive sunflower motley and purchase certified disease - free seed can serve you avoid transmission .
Foliar fungicide wo n’t do much , though . If your plants are infect , off and dispose of them in the trash .
Also sleep with as Phoma blight , Phoma black-market stem turn has one very obvious symptom – I ’m sure you may forecast out what it is .
This disease is because of the fungusPhoma macdonaldii , which survives in seeds or on infected crop remainder and is spread by worm such as helianthus stem weevil , Apion occidentale .
And as with many fungous condition , wet atmospheric condition promote the evolution of this disease .
Once infected , the plant will exhibit one- to two - inch pitch-dark lesions on the theme . Additional dark spots can show up on the leaf and flowers , theentire flora can droopand dry out up , and bloom can die .
Cleaning up plant balance at season ’s end , growing hybrid mintage , and rotating your sunflowers every three years can help fend off this disease , along with managing thelocal pest populations .
Fungicides wo n’t do much for control , so it ’s best to off and sales talk infected specimen .
Avoid planting sunflowers in the same locating the next season .
This disease can be well confused with Phoma black stem , for a few reason .
induce by fungal species in theDiaporthegenus , the pathogen overwinter in plant detritus . contagion usually go on during moist conditions like pixilated weather condition and high humidity .
And italsoproduces gnarly stem wound – although they ’re larger than those of Phoma bleak stem , and browned in color rather than bootleg .
Infected leaf will train little brown bit , which eventually commingle into large dark-brown division of foliar decline . In addition to look filthy , infected specimen are prompt to droop and die .
To prevent this disease , ensure enough air flow between plants , clean up craw debris , rotate your plantings , and if you ’ve had a trouble in the past , prefer repellent hybrid .
For command , you may apply copper fungicide when the flower head have just mould . Otherwise , remove and demolish gravely symptomatic plants .
Once again , forefend planting sunflowers in the same place the following time of year and prefer something that does n’t play host to these pathogen , like pale yellow or corn .
pull round as mycelium in plant detritus , the fungous pathogenErysiphe cichoracearumspreads via wind or slosh water system to new , clean leafage .
contagion and disease development is most likely in humid atmospheric condition , yet while the foliage remains ironical .
The independent symptom is leave coated with a off-white - gray gunpowder . Additionally , leafage could uprise small , black hint of spore - producingcleistothecia , which will surpass the trouble onto other specimens .
Thankfully , this consideration is mostly a cosmetic issue , as infection are n’t usually fateful .
To prevent powdery mildew , insure your sunflowers have full sun exposure and be sure to space them to allow for sufficient zephyr circulation .
Trim away diagnostic leave as you notice them , and consult our guide tolearn more about how to manage powdery mildew .
Puccinia helianthiis the fungal species that causes rust fungus in sunflowers .
The pathogen live on in dead and decay plant life topic over the winter and attacks your sunflowers when they are lactating from haste or irrigation .
Infected sunflower will exhibit rust - colored , xanthous - ringed growths on the foliage which produce spores that spread via wind to other plants . If transmission is severe enough , defoliation can occur .
If symptoms are severe , take out up and disposing of septic industrial plant may be your best option .
Septoria leaf fleck disease is due to the fungusSeptoria helianthi .
This disease tend to modernise quickly in warm condition and in times of high rain . The pathogen is mostly spread via spatter water , and overwinters in plant life residual .
Symptoms include body of water - soaked , round light-green - gray lesions on the foliage , which are usually resound with greensick tissue paper .
In fourth dimension , diminished spore - producing smear will also mould on the underside of leaves , and infected plants could develop a deplorable - sounding , watery wilt disease before they die .
Diseased leafage leads to reduced photosynthesis , which result in stunted growth .
To prevent Septoria foliage situation , circumvolve your plantings every three years at least , avoid sprinkle the leave of absence with pee when you irrigate , and buy manifest disease - free seminal fluid .
Cleaning up works junk at the terminal of the time of year denies the pathogen a seat to overwinter . If your plants are infected , pull them up and cast away of them in the rubbish .
Health Is Wealth, Y’all
It ’s true for hoi polloi , and it ’s true for sunflowers .
Most of these disease can be avoid by spring up these annuals in a full sun location , maintaining adequate air flow between plant , and water at soil grade instead of from command processing overhead .
At season ’s ending , clean up beds and mete to preclude disease - causing pathogens from overwintering in dead plant tissue paper .
And formore information about produce sunflowers in your garden , read these guide next :
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Joe Butler
