Preliminary evaluation of guava selections for guava wilt disease resistance in South Africa

Abstract

Guava wilt disease (GWD), caused by

Efficacy of fungicides, plant resistance activators and biological control agents against guava wilt disease caused by Nalanthamala psidii

“…The plants were 30 cm in height and were planted in 4L capacity black plastic bags (Dimensions: 20cm height and 15cm diameter) containing composted pine bark medium Pathogen inoculum was produced by growing three isolates of N. psidii (FR, G2 and G1) (Schoeman and Labuschagne 2014) separately on malt extract agar plates (90 mm diameter) for 10 days at 25°C. For inoculation, three culture plates (one per isolate) were macerated together in 2L of sterile water for 1 minute and 200ml of the resulting suspension applied per plant bag as a drench treatment.…”

“…1200 ha in 2014 (Schoeman & Labuschagne 2014). The largest production area was the Western Cape Province (547 ha), followed by the Limpopo Province (442 ha) and the Mpumalanga Province (140 ha).…”

“…GWD is also present in South-east Asia where it is caused by the same fungus as in SA (Schoeman & Labuschagne 2014). A different wilt disease of guava caused by Fusarium oxysporum f. sp.…”

“…The largest production area was the Western Cape Province (547 ha), followed by the Limpopo Province (442 ha) and the Mpumalanga Province (140 ha). The area under guava production is however diminishing at a rapid rate in the Mpumalanga and Limpopo provinces due to a devastating wilting disease (Schoeman & Labuschagne 2014).…”

“…This suggests that a new virulent strain / race of N. psidii has evolved, placing the guava industry under threat once again. Long term measures currently undertaken to address this new threat include further in vitro screening of thousands of guava seeds using cell free filtrates derived from the newly-isolated N. psidii strains (Schoeman & Labuschagne 2014). As a short term solution chemical and biological control products are being screened.…”