A Trial of Estimating Number of Leaf Blast Lesions on Rice Plants on the Basis of the Number of Trapped Spores and Wetting Period of Leaves

Kim, Chang Kyu; Yoshino, Reiichi; Mogi, Shizuo

doi:10.3186/jjphytopath.41.492

Cited by 3 publications

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“…The dew formation on the leaf surface is one of the main factors which are responsible for outbreak of rice blast (Burrage, 1971;Long, 1955;Long, 1958;Monteith and Butler, 1979;Wallin, 1963). Persistence of guttation/dew droplets for a while on the leaf surface is a requisite for contagions with rice blast (Hashimoto et al, 1984;Hemmi and Abe, 1931;Kim et al, 1975;Yoshino, 1979). In our previous study (Taguchi et al, 2014), outbreaks of rice blast (both leaf and panicle blasts) were remarkably prevented by sending artificial wind which was generated 2 times daily for 30 min each starting at 11:00 PM and 4:00 AM, respectively, to the paddy fields to prevent leaf surfaces from remaining moist longer than 8 h, which is sufficient time for blast fungus infection (Hashimoto et al, 1984;Yoshino, 1979).…”

Section: Leaf Positionmentioning

confidence: 99%

Effect of artificially-generated wind on removing guttation and dew droplets from rice leaf surface for controlling rice blast disease

Taguchi¹,

Elsharkawy²,

Hyakumachi³

2015

Afr. J. Biotechnol.

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The incidence and severity of leaf and panicle blasts were efficiently reduced in the wind-treated fields. Artificially-generated wind was performed on rice paddy field in order to measure the changes in temperature and humidity during and after the blowing process and to investigate the effects of sending wind on the formation and removal of guttation and dew droplets on rice leaves. A large electric fan was used to send wind with a depression angle of 30° at 4:00 AM for 30-40 min. During the blowing process, the humidity percentage was 100% in both treated and control paddy fields, the temperature was 0.8°C higher in the treated than the control field and the dew weight was rapidly decreased from 21 to 8 g in 20 min in the treated field. After the blowing process, the temperature started to rise at 6:28 AM (10 min earlier than the control block). It reached 29°C at 6:48 AM (30 min earlier than the control block) and remained higher than the control block till 7:20 AM (1-7°C higher). The humidity decreased to 95% at 6:30 AM (20 min earlier than the control block) and remained 95% till 6:42 AM, then rapidly decreased to reach 68% at 6:46 AM, and finally reached 60% at 7:20 AM. The humidity was 5-30% lower than that in the control block. Moreover, the dew weight increased to the initial level within 10 min and then decreased rapidly in both blocks starting from 6:20 AM. Using wind speed of 4.3 m/s or 3.2 m/s for 60 s per rotation at 4:00 AM, almost all the guttation droplets except those of less than 0.5 mm were removed from the surfaces of the 1 st and 2 nd uppermost leaves after two rotations (at velocity 4.3 m/s) or three rotations (at velocity 3.2 m/s) and the dew droplets were mostly removed after five rotations (at velocity 4.3 m/s) or nine rotations (at velocity 3.2 m/s). Sending wind at a speed of 3.2 m/s or faster removed guttation and dew droplets and suppressed the subsequent dew formation. Our data indicates that the removal of dew droplets on rice hills resulted in reduction of the disease development of Pyricularia oryzea.

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