Fusarium basal rot (Fusarium oxysporium f.sp. cepae)
The above ground symptoms constitute yellowing of leaf blades at the tip. The yellowing at later stages covers the whole blade. The affected leaves shrivel and decay. Diseased plants can be easily pulled out because the root system is rotted. Affected roots are dark brown, flattened, hollow and transparent. When diseased bulbs are cut vertically, a brown discolouration is evident. The fungus survives in any soil moisture that permits crop growth. Infection is facilitated by injuries to root system, Losses can occur in the field and in storage.
The disease is most prevalent where onions are grown under high temperature conditions. Although of no economic importance the disease could attack garlic, shallots, chives and leeks. It also can survive in weed, Oxalis corniculata.
- Rotate with non-related crops.
- Avoid root injury.
- Carefully harvest the bulbs.
- Proper cure the bulbs before storage.
- Store the bulbs at 0°C / 65-75% relative humidity is recommended.
Fusarium basal rot (Fusarium oxysporium f.sp. cepae) dalili za juu ya ardhi hufanyiza manjano ya blades ya majani kwenye ncha. Katika hatua za baadaye, rangi ya manjano hufunika kisu chote. Majani yaliyoathiriwa hufifia na kuharibika. Mimea iliyoambukizwa inaweza kuondolewa kwa urahisi kwa sababu mfumo wa mizizi umeharibika. Mizizi iliyoathiriwa ni ya rangi ya kahawia-nyeusi, imepigwa, ni tupu na ni ya uwazi. Matofali yenye magonjwa yanapokatwa wima, rangi yake huwa kahawia. Uyoga huo huishi katika unyevu wowote wa udongo unaoruhusu ukuzi wa mazao. Maambukizi ni kuwezeshwa na majeraha ya mfumo wa mizizi, hasara inaweza kutokea katika uwanja na katika kuhifadhi. Ugonjwa huo huenea zaidi mahali ambapo vitunguu hukua chini ya hali ya joto la juu. Ingawa ugonjwa huo haukuwa na umuhimu wowote kiuchumi, ungeweza kushambulia vitunguu, shaloti, chives na leeks. Pia inaweza kuishi katika magugu, Oxalis corniculata. - Zungusha na mazao yasiyo na uhusiano. - Epuka kuumiza mizizi. - Kukusanya kwa uangalifu bulbs. - Paka balbu vizuri kabla ya kuzihifadhi. - Kuhifadhi bulbs katika 0 ° C na unyevu wa jamaa wa 65-75% ni ilipendekezwa.