Control of Fusarium wilt in banana with Chinese leek

Abstract

The inhibitory effects of Chinese leek(Allium tuberosum) on Fusarium oxysporum f. sp. cubense (Foc) and on Fusarium wilt incidence were studied in order to identify a potential efficient way to control the disease. Adopting the rotation system of Chinese leek-banana reduced the Fusarium wilt incidence and disease severity index by 88 %-97 % and 91 %-96 %, respectively, improved the crop value by 36 %-86 %, in an area heavily infested by Foc between 2007 and 2009. As a result of inoculation in the greenhouse, Chinese leek treatment reduced disease incidence and the disease severity index by 58 % and 62 %, respectively in the variety Baxi (AAA) and by 79 % and 81 %, respectively in the variety Guangfen NO.1 (ABB). Crude extracts of Chinese leek completely inhibited the growth of Foc race 4 on Petri dishes, suppressed the proliferation of the spores by 91 % and caused 87 % spore mortality. The findings of this study suggest that Chinese leek has the potential to inhibit Foc growth and Fusarium wilt incidence. This potential may be developed into an environmentally friendly treatment to control Fusarium wilt of banana.

Figure 1

Plantations of Guangfen No.1 (ABB) rotated with different crops in Panyu, Guangzhou, China in rotation with Chinese leek (a) rice (b), sugarcane (c) other vegetables (d). Symptoms in (b)-(d) are typical for Fusarium wilt.

Figure 2

Potted bananas 180 days after inoculation with Foc race4 in the greenhouse. Banana varieties Baxi (AAA) (a) and Guangfen NO.1 (ABB) (c) plantlets treated with Chinese leek developed in good health. The untreated control plantlets of Baxi (AAA) (b) and Guangfen NO.1 (ABB) (d) showed clear disease symptom.

Figure 3

Inhibitory effects of Chinese leek on Fusarium wilt incidence (a), disease severity index (b), and AUDPC(c) in potted banana plantlets inoculated with Foc race4. AUDPC was calculated from 90 to 180 days after inoculation(TR: Treatment, CK: Control). Values are the means of three replications with 20 plants in each treatment and vertical bars indicate the standard errors of the means.

Figure 4

Effect of crude extract of Chinese leek on the proliferation and fluorescence of spores of Foc race 4. Two ml of spores (10⁶ spores/ml) of Foc race 4 labelled with green fluorescent protein were co-cultured with 0 ml (a), 1 ml (b), 5 ml (c), and 10 ml (d) of crude extract of Chinese leek leaves per 20 ml culture on a shaking table for 16 h, and then were detected with a Zeiss LSM510 laser scanning confocal microscope (Carl Zeiss, German) using a Plan-Neofluar 40× /1.3 oil DIC objective. Black arrows indicate dead spores without fluorescence reaction, white arrows indicate the live spores with fluorescence reaction.