Dear Alex

There are many reasons for chlorosis and browning of sunflower. Pseudomonas syringae is a well-known causal agent for apical chlorosis of sunflower. Also micronutrient deficiencies and specially Boron and Iron elements is another reason. Also the effects of pesticides residues could be considered.

There are many reasons for seedling chlorosis . However,from the photograph,it may be some viral infection.

There are many reasons for chlorosis (chlorophyl deficiency) including mineral deficiency, incorrect soil pH, poor drainage, toxins, pathogens, etc. Brown tips is usually caused by shallow watering

Dear;

There are many reasons for the question;

so, i agree with answer of Mohammad Mehdizadeh

Best regrds

Sunburn damage?

Dear Alex, I agree with Mohammad, because the cotyledons are affected by browning and chlorosis, a seed-borne infection by fungi or bacteria could be the cause. Please make the moist chamber test with the seeds: take a Petri dish, put filter paper in it, moisten it (aqua dest.) and lay single seeds on it with a distance of about 2 cm. It is better to do a surface sterilization of the seed with 70% alcohol or 0,1% sublimate in order to exclude the action of superficially adhering fungal spores. Close the Petri dish. Store at 15-20°C. Check every day for mycelium(fungi) or mucus drops (bacteria). Choose them if you find them. If you find any, the symptoms most likely have an abiotic cause: micronutrient deficiencies, to high humidity or phytotoxic side effects of herbicides (mostly) or insecticides or fungicides for seed treatment. Ask if herbicides, insecticides or fungicides was applied at all.

From pic of seedlings there could be two reason. 1. micro-nutrient deficiency. 2. Viral/bacterial infection. Test as suggested by Petra Seidel

Over watered seedlings?

Dear All,

Thank you for your opinions! By now, diseased seedlings are growing slower. I would rule out idea about micronutrient deficiency - healthy plants have the same soil and optimal water supply with microelements.

Isolation of possible bacteria was done, I am waiting for results.

phytotoxic side effects of pesticides is still possible.

With best wishes

Alex

Stress (abiotic and biotic), infection (bacteria virus or even fungi) etc. as experts mentioned above. Thanks ALL

Dear Alex

I agree with Petra Seidel you need to do a seed health test to detect which pathogens are inside the seeds.

You can also do a test by placing cotyledon leaves with symptoms in a humid chamber under a 12 hour regime in the dark and 12 hours light to promote sporulation of the fungus. If it is a fungus in three or four days you will notice sporulation under the microscope stereoscope.

If there is no sporulation or fungal mycelium then probably the cause of the disease will not be fungus.

The humid chamber can be made as Petra suggested. You should separate some petri dishes to put only the leaves and cotyledons with symptoms.

Here's how it can be done.

Hi, Mite damage give like this symptoms, you should check under microscopic for any, otherwise it look like phytotoxicity problem.

@All, thank you for the ideas. So far, I have isolated from cotiyedons only slow growing yellow bacteria of genus Curtobacterium. Really, I was confused by large number of symptomatic plantlets.

Hi Alex.

I've been thinking: if you still have some seeds you could sow them in autoclaved sand. Put 200 seeded seeds in two rows of 100 seeds and place them away from the plants where the sick are. Do this in a suitable environment with a temperature around 25 ° C and do the irrigation within the field capacity. It accompanies the germination for seven days. If the problem continues is because the seed is actually infected. If the symptoms do not appear it is because the pathogen is in the substrate or there was contamination or phytotoxicity by products applied in the plants near their trays.

So far, Curtobacterium flacumfaciens is the most probable agent of the disease. It was re-isolated from all symptomatic plants. Some pathogenic Pseudomonads close to P. marginalis have contributed to stem damage just above soil level.

Alex

Yes. I found two bibliographical references on Curtobacterium flaccumfaciens pv. Flaccumfaciens. One in Brazil reports the transmission of this bacterium in bean and another very old one that reports the occurrence of this pathogen in oilseeds including sunflower.

I think you are right about the causative agent of this disease because you have found signs and symptoms on all infected parts and the literature confirms the transmissibility of the pathogen by the seeds

Now, you will have to look for healthy seeds to give continuity to your work. Do not forget to take the health seed test to prove the sanitary quality of your seeds before starting your work.

Good luck!

Article Curtobacterium Flaccumfaciens pv. flaccumfaciens detection i...

https://books.google.com.br/books?id=CNHoRfS0e04C&pg=PA554&lpg=PA554&dq=Curtobacterium+flaccumfaciens+and+sunflower+seeds&source=bl&ots=lc-1eoPNx9&sig=tw4QMDFy5fivhT00e8AMTUHdi5Q&hl=pt-BR&sa=X&ved=2ahUKEwjH4P_QvObcAhXBS5AKHbWRBWkQ6AEwD3oECAQQAQ#v=onepage&q=Curtobacterium%20flaccumfaciens%20and%20sunflower%20seeds&f=false

Maria, thank you a lot! I believed that it is a new disease, but now we can say that seed company must test stocks for the pathogen.

Alex

Alex.

You have all the arguments to denounce the company to the Ministry of Agriculture of your country and ask them to inspect the company responsible for the production and distribution of these seeds.

The company must withdraw this batch of circulation seeds to prevent sunflower growers from having significant economic losses due to the introduction of a new disease in their fields.

It is lacking of responsibility with the producer. You lost time and some seeds, the producer will be losing a lot of money and still introducing a new disease in the region or in the country, since the seed spread guarantees the establishment of the disease.

Do not let producers fall prey to company neglect.

Every seed-producing company must have in its team of professionals a seed pathologist who certifies the phytosanitary quality of its seeds

Best Regards

Dear All,

thank you for your advices. We will search for this new pathogen in seed stocks of sunflower. Maybe, the result will convince seed companies to pay more attention to bacterial diseases.

Happy New Year!

Alex

Also for you, Alex, a happy New Year! Petra

Hi Alex

his reference may be useful = Tocopherols in Sunflower Seedlings

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&cad=rja&uact=8&ved=2ahUKEwiQmu7Y-efgAhUCr6QKHWwECQ0QFjAGegQIBhAB&url=https%3A%2F%2Fwww.hindawi.com%2Fjournals%2Ftswj%2F2015%2F146782%2F&usg=AOvVaw3ORS1M18_wiIFB4qvKV6Rq

Ref.2 = cotyledon leaves of a young

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=14&cad=rja&uact=8&ved=2ahUKEwiQmu7Y-efgAhUCr6QKHWwECQ0QFjANegQICBAB&url=https%3A%2F%2Fwww.cabi.org%2Fisc%2Fdatasheet%2F41911&usg=AOvVaw1WI67viByn3O81DUkXgW8Z

Ref.3 = Leaf chlorosis on sunflower cotyledon leaves

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=15&cad=rja&uact=8&ved=2ahUKEwiQmu7Y-efgAhUCr6QKHWwECQ0QFjAOegQIAhAB&url=http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1111%2Fj.1365-2338.2008.01245.x%2Fpdf&usg=AOvVaw2bra8cT5JGI669OnhGjSLd

Ref.4 = lesions on seedling cotyledons

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=16&cad=rja&uact=8&ved=2ahUKEwiQmu7Y-efgAhUCr6QKHWwECQ0QFjAPegQIARAB&url=http%3A%2F%2Fwww.apsnet.org%2Fpublications%2Fplantdisease%2F2009%2FDecember%2FPages%2F93_12_1351.1.aspx&usg=AOvVaw1xE3sJFUHluwX1QGmMKD6u

Ref.5 = chlorotic sections of leaves of the toxin-affected sunflower plants

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=20&cad=rja&uact=8&ved=2ahUKEwiF8e77-ufgAhUGEVAKHe75BRw4ChAWMAl6BAgDEAE&url=https%3A%2F%2Fwww.jstor.org%2Fstable%2F10.1086%2F382799&usg=AOvVaw1HFA4XzaMj5wI0f4gEX_9-

Ref.6 = Etiolation Symptoms in Sunflower

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=16&cad=rja&uact=8&ved=2ahUKEwie2vCv--fgAhVKC-wKHdxnBUEQFjAPegQIABAB&url=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC2802920%2F&usg=AOvVaw3M5RrOuQKSU8uMwae96ktC

== Chlorosis and browning of young leaves

https://books.google.com.my/books?id=_55yK0hj67IC&pg=PA5&lpg=PA5&dq=chlorosis+and+browning+%2B+cotyledons+%2B+sunflower+seedlings&source=bl&ots=WtX4xpzh4X&sig=ACfU3U3-tCxnFPE3SGIm5OWOj5ph-hGizQ&hl=en&sa=X&ved=2ahUKEwie2vCv--fgAhVKC-wKHdxnBUEQ6AEwDnoECAIQAQ

= ==== yellow (chlorotic) or brown (necrotic) and the leaves

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=19&cad=rja&uact=8&ved=2ahUKEwjSro_q--fgAhVCI1AKHYt0AhI4ChAWMAh6BAgBEAE&url=http%3A%2F%2Fwww.cof.orst.edu%2Fcof%2Ffs%2Fkpuettmann%2FFS%2520533%2FVegetation%2520Management%2FHerbicide%2520Mode%2520of%2520Action%2520and%2520Injury%2520Symptoms.htm&usg=AOvVaw1f5Bpfcs0y4NIsUDA2glPT

==== chlorosis and necrosis

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=20&cad=rja&uact=8&ved=2ahUKEwjSro_q--fgAhVCI1AKHYt0AhI4ChAWMAl6BAgCEAI&url=http%3A%2F%2Fwww.pakbs.org%2Fpjbot%2FPDFs%2F40(2)%2FPJB40(2)759.pdf&usg=AOvVaw0KcC79YeZmp91XN5pOdeoe

===== Herbicide Mode of Action and Injury Symptoms

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=40&cad=rja&uact=8&ved=2ahUKEwjEoviC_efgAhVPJFAKHS7WA8c4HhAWMAl6BAgAEAI&url=http%3A%2F%2Fwww.appliedweeds.cfans.umn.edu%2Fsites%2Fappliedweeds.cfans.umn.edu%2Ffiles%2Fherbicide_mode_of_action_and_injury_symptoms.pdf&usg=AOvVaw2Cf054PZTJAA8x2yIzkHRi

Dear Laith Al-Ani,

Thank you a lot for large amount of information.

Alex

You are welcome