გლობალური: კვლევის თანახმად, შავი ქერქის წარმოქმნა ნაყოფის განადგურებიდან 3-6 დღეში შეიძლება დაიწყოს
ძირითადი მიღება
- 3-6 დღის შემდეგ haulm kill, tuber surface changes begin
- 20 sclerotia per side of washed tuber: consider new seed
- 2 inches (about 5 cm) is the maximum soil cover on seed
- 2 consecutive potato seasons on one field should be avoided
რატომ არის მნიშვნელოვანი
- ფერმერებისთვის
- Plan harvest to start as soon as skins are firm after haulm kill, and count sclerotia on washed seed samples before buying seed
- ტრეიდერებისთვის
- Check washed samples for black scurf before buying seed or pre-pack lots, since appearance sets the price
- მომწოდებლებისთვის
- Offer seed lot sclerotia counts on washed samples and advise on haulm destruction methods that limit black scurf
60-წამიანი შეჯამება
The period between killing the haulm and lifting the crop is where black scurf is won or lost. Dutch research found that tuber skins start changing within three to six days of haulm destruction, and those changes encourage Rhizoctonia to lay down sclerotia. Pulling the haulm, or severing roots after chemical desiccation, slowed the process and widened the window for lifting firm-skinned, clean tubers. Extension advice from Maine and Cornell matches this: the longer tubers sit after vine kill, the more scurf, so harvest promptly once skins hold. Seed remains the main carrier; Maine suggests a new seed source when a washed tuber shows over twenty sclerotia on one side, plus shallow planting and no potatoes after potatoes. Seed growers and washed-pack suppliers feel the cost most. The 3 to 6 day figure comes from a single older thesis, and local conditions may shift the timing.
Black scurf is the name for the hard black sclerotia that Rhizoctonia solani leaves on potato skins. They do not rot the tuber. But they spoil the look of ware potatoes and carry the fungus into the next crop through seed.
The key period is the gap between haulm destruction and harvest. A Wageningen doctoral study by G. Dijst in 1989 examined this gap. It found that haulm destruction stimulates black scurf formation, because the tuber surface changes as the tuber matures faster. These changes probably start within 3 to 6 days, the study said.
მეთოდი haulm destruction mattered more than the variety or the level of seed infestation. Haulm pulling stimulated black scurf less than chemical haulm destruction or cutting the shoots. Cutting the roots as well moderated black scurf formation. It also extended the period in which tubers could be lifted with a firm skin and limited black scurf.
სამუშაო დღეებში. გამოწერის გაუქმება ერთი დაწკაპუნებით.
Extension advice
Current extension advice follows the same line. Sclerotia formation increases as the interval between vine kill and harvest is lengthened, according to a University of Maine bulletin reviewed in 2020. Cornell University advises harvesting soon after vines are killed. Its fact sheet, updated in April 2021, notes that sclerotia begin to form on tubers as vines senesce.
Seed is the main source of infection. Tuber inoculum is more important than soil inoculum, the Maine bulletin says. It gives a simple rule: if more than 20 sclerotia are visible on one side of washed tubers, consider a different seed source. It also advises covering seed with no more than two inches of soil, about 5 cm, to speed emergence. At a minimum, potatoes should not follow potatoes on the same land in two consecutive seasons.
Cornell adds that damage is worst in cool, wet soils, especially when the weather is cold and wet in the weeks after planting.
რატომ არის მნიშვნელოვანი
Growers wait after haulm kill so that the skin sets and resists harvest damage. But every extra day in the soil gives the fungus more time to form sclerotia. The two goals pull in opposite directions.
The practical answer is to plan both together. Start with clean seed and a sensible rotation. Choose a haulm destruction method that slows scurf. Then lift as soon as skins are firm, rather than leaving tubers in the ground longer than needed. This matters most for seed crops and for washed ware potatoes, where appearance sets the price.
Photo: Black scurf (Rhizoctonia solani) on potato tubers (illustrative). Jerzy Opioła / ვიკიპედია, CC BY-SA 4.0
გლობალური კარტოფილის მიმოხილვა
ხუთი საუკეთესო სიახლე, ფასები, დაავადებების შესახებ შეტყობინებები და ღონისძიებები. სამუშაო დღეებში დილაობით, რეკლამის გარეშე.
წყაროები
- Wageningen University, G. Dijst — The effect of chemical haulm განადგურება და haulm pulling on potato black scurf caused by Rhizoctonia solani AG-3 (PhD thesis, 1989) — https://research.wur.nl/en/publications/the-effect-of-chemical-haulm-destruction-and-haulm-pulling-on-pot/
- University of Maine Cooperative Extension Bulletin 2273 — Potato Facts: Rhizoctonia Diseases on Potatoes (2003, reviewed 2020) — https://extension.umaine.edu/publications/2273e/
- Cornell University — Rhizoctonia Canker and Black Scurf of Potato (updated April 2021) — https://www.vegetables.cornell.edu/pest-management/disease-factsheets/rhizoctonia-canker-and-black-scurf-of-potato
ბმული ამ მასალაშია
- ქვეყანა
- მსოფლიო
- განყოფილებები
- დალაგებასიახლეები - HUASHILროპის დაცვა
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გლობალური: კარტოფილის დაშვების სიმაღლე 15 სმ-ზე ნაკლები უნდა იყოს, აჩვენებს დარტყმის ჩამწერი კვლევები
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