Effect of Nitrogen Fertilization on Disease Progress of Rice Blast on Susceptible and Resistant Cultivars

Abstract

The effects of three nitrogen fertilization treatments on the development of rice blast were studied on eight cultivars under field conditions in Arkansas in 1995 and 1996. The eight cultivars (Kaybonnet, Cypress, Lacassine, Mars, Adair, Alan, Newbonnet, and RT7015) ranged from resistant to susceptible to blast according to previous field observations. The recommended nitrogen levels for the eight cultivars varied from 123 to 168 kg/ha/year. Three treatments, consisting of different rates and timing of nitrogen applications, were tested over 2 years at one location. The first treatment consisted of a single nitrogen (N) application applied to plots at the recommended rate at preflood during the midtillering stage. The second treatment consisted of applying nitrogen as a single preflood application but at 1.5 times the recommended N rate used in treatment one. The third treatment (control) consisted of applying the recommended amount of nitrogen fertilizer used in treatment one, but in a three-way-split application with 56 to 100 kg/ha (depending on the cultivar) of urea applied at preflood followed by the application of 34 kg/ha of N applied approximately 10 and 20 days after the panicle differentiation (PD) growth stage. Inoculated spreader plots were used to initiate rice blast epidemics in the test plots. The results indicate that the disease progress for rice blast, regardless of N treatments, followed a unimodal curve, whereby disease incidence and total lesion area per plant reached a maximum near midseason (PD growth stage) and then gradually declined. This decline in disease was attributed to adult resistance, leaf senescence, and the formation of new (noninfected) leaves. Application of nitrogen above the recommended rate for any given cultivar significantly increased disease incidence and total lesion area per plant on all cultivars except Kaybonnet, a highly resistant cultivar. Furthermore, a differential cultivar response to nitrogen was observed when measuring both disease incidence and total lesion area per plant. Leaf blast was significantly more severe on the susceptible and very susceptible cultivars when N fertilizer was applied as a single application at preflood than in the split application treatment. Nitrogen treatments did not significantly affect the incidence of collar rot or neck blast.

Plant species diversity for sustainable management of crop pests and diseases in agroecosystems: a review

“…Agricultural practices that lead to significant discrepancies in nitrogen availability (in terms of quantity, form and balance with other nutrients) are likely to result in variations in the incidence of diseases such as rice blast (Primavesi et al 1972;Séguy et al 1981Séguy et al , 1989Long et al 2000;Walters and Bingham 2007). High concentrations of these compounds in plant cells also make them more attractive to certain pests, particularly sucking insects (Chaboussou 2004;Jahn et al 2005;Lu et al 2007).…”

The role of sugar signaling in plant defense responses against fungal pathogens

“…Rice blast (Kürschner et al 1992;Long et al 2000) is the best-known example of such a disease. Among wheat diseases, powdery mildew (Last 1953;Teich et al 1987), leaf rust (Howard et al 1994;Teich et al 1987), stripe rust or yellow rust (Ash and Brown 1991;Danial and Parlevliet 1995) and several other diseases (Howard et al 1994) have been reported to increase in severity as the rate of nitrogen application is increased.…”

Resistance to neck blast caused by Pyricularia oryzae in Italian rice cultivars

“…Disease management is based mainly on efficient use of nitrogen fertilization (Webster and Gunnell 1992;Long et al 2000), use of resistant cultivars, crop rotation, maintaining a proper flood level and treatment with fungicides (TeBeest et al 2007;Maciel 2011). Surveys conducted in 2009 showed that in Italy the 75 % of the rice area is treated against blast disease and the 94 % of treated surface is treated with tricyclazole, mainly by a single treatment (Di Tullio and Baldi 2011).…”