Sugarcane rust pathogens and their management: emerging strategies

Since the late 1970s, sugarcane rusts have become increasingly important as airborne fungal pathogens of sugarcane. Three types of rust diseases are known. These diseases are a concern in sugarcane-growing countries, and their unchecked spread from one country to another threatens both sugar yields and farmers’ livelihoods in sugarcane-dependent economies. For example, Brown rust (Puccinia melanocephala) has been reported to cause 10%–50% yield losses in susceptible varieties, and Orange rust (Puccinia kuehnii) causes up to 50% yield reduction in Australia. This paper describes some key aspects of the three diseases and current management practices. Two new avenues could contribute to their sustainable management. Applications of silicate-based products aim to reinforce the plant cell wall structure, thereby increasing resistance to rust pathogens and, in general, to other diseases and pests. The use of naturally occurring mycoparasites of rusts, such as Sphaerellopsis filum, Lecanicillium spp. and other mycoparasites, is another novel strategy that needs to be explored for the ability of mycoparasites to lower inoculum pressure. These ecofriendly measures could provide a sustainable approach towards rust management, expanding the portfolio of control methods.