Chemical Control of Basal Rot of Onion in Zambia

Abstract

In a commercial planting of onion, root and basal rots reduced establishment of sets to 44%. which with 30% basal rot in harvested bulbs, represented an overall numerical loss of potential yield of 69%. Fusarium oxysporum, already present in sets at planting, contributed to poor establishment. Isolation from seedlings grown for sets in virgin soil at three locations yielded infection rates of 80 to 90%. In two field trials to evaluate fungicide treatments mean establishment was 47%. In the f i r s t trial involving dusting of the sets before planting Granosan 200 (benomyl 15% + mancozeb 60%) increased establishment by 28%. reduced basal rot of harvested bulbs by 77% and increased yield by 106%. Benomyl decreased basal rot and increased yields but captan and thiram treatments were ineffective. When bulbs from this trial were stored for six weeks under ambient conditions losses were 94% in controls and 45% in the benomyl + mancozeb treatment, with losses from other treatments intermediate. In the second trial, using pre-planting dips of benomyl the optimum concentration/tinp of 100 M/ml for 15 min, reduced basal rot by 65% and increased yield 54%.

Fusarium basal rot: profile of an increasingly important disease in Allium spp.

“…Pre-planting dipping of onion bulbs with benomyl (100 μg.mL −1 for 15 min.) reduced basal rot by 65% and enhanced yield with 54% (Naik and Burden 1981). Similar results were obtained when combined with vinclozolin (Özer and Ömeroğlu 1995) or mancozeb (Naik and Burden 1981).…”

“…Even when cultivated in virgin soil, the presence of FBR is quite high as observed in Zambia, where 80-90% of the transplants were infected by F. oxysporum f. sp. cepa, resulting in enormous losses in post-transplanting seedlings (44%) and potential yield (69%) (Naik and Burden 1981). The level of losses is usually higher in organic farms than in conventional farms (Haapalainen et al 2016).…”

“…Carbendazim, benomyl, and prochloraz are mostly used, alone or in combination with other fungicides to control FBR via a soil treatment (Abd-Elrazik et al 1990;Naik and Burden 1981;Özer and Köycü 1998;Sintayehu et al 2011). Seed treatments with benomyl and thiram resulted in a limited seed contamination of F. oxysporum, improved seedling emergence, and reduced damping-off, whereas seed coating with prochloraz provided remarkable protection in infested soil (Özer and Köycü 1998).…”

Biological Management of Basal Rot of Onion by Trichoderma harzianum and Withania somnifera

“…Application of Granosan 200 (benomyl 15% + mancozeb 60%) declined this disease by 77%, consequently onion yield was increased by 106% (Naik and Burden, 1981). Recently, Behrani et al (2015) found carbendazim and antracol very effective in controlling basal rot of onion.…”

Seed-borne Fungal Diseases of Onion, and their control

“…F. oxysporum f. sp. cepae reduces seed yield, germinability, 1000 seed weight (Barnoczki-Stoilova, 1986) and generally kills young seedling at pre-and post-emergence stages (Naik and Burden, 1981;Kodama, 1983;Srivastava and Qadri, 1984;Özer and Köycü, 1997). Symptoms on set bulbs are difficult to observe.…”