Agriculture Reference
In-Depth Information
Table 2.6. Examples of critical-point yield loss models for cereal diseases (Cook and
King, 1984)
Disease
Relationship
Spring barley
Mildew
y
= 2.5
√
x
i
Brown rust
y
= 0.4
x
ii
Rhynchosporium
y
= 0.5
x
ii
Winter wheat
Mildew
y
= 2.0
√
x
i
Septoria
y
=
x
iii
Yellow rust
y
= 0.4
x
iii
Eyespot
y
= 0.1
x
m
+ 0.36
x
s
Sharp eyespot
y
= 0.05
x
m
+ 0.26
x
s
y
= % loss in grain yield,
x
i
= % disease on leaf 3 at GS 58,
x
ii
= % disease on leaf 2 at GS 75
,
x
iii
= % disease on flag leaf at GS 75,
x
m
= % tillers with moderate symptoms at GS 75,
x
s
= % tillers with severe symptoms at GS 75.
Figure 2.11. Estimated yield loss from epidemics of potato late blight in which the 75%
disease level (the critical disease severity) is reached at differing times during the season.
(After Large, 1952; Crown copyright, 1986).
