Agriculture Reference
In-Depth Information
5.3.4.3
PEST AND DISEASES
Higher rainfall and humidity is congenial for increasing disease intensity
in potato, such as late blight (
Phytophthora infestans
), especially when
combined with longer growing seasons. Bacterial wilt may also increase
as the climate becomes warmer and wetter and potato pests, including
disease-carrying aphids, will survive at higher altitudes. With the rise in
temperature and humidity the new biotype of diseases will emerge which
is tolerant to varied climatic condition. Soil born disease like bacterial wilt
(
Ralstonia solanacarum
) will be more problematic which can grow up to
40
0
C (Masao Gato, 1992).
Jeong et al. (2010) in his investigation under future climate change
condition treatments in growth chambers experiment on four major dis-
eases of chili pepper including two fungal diseases, anthracnose (
Col-
letotrichum acutatum
) and Phytophthora blight (
Phytophthora capsici
),
and two bacterial diseases, bacterial wilt (
Ralstonia solanacearum
) and
bacterial spot (
Xanthomonas campestris
pv.
vesicatoria
). Treatments with
elevated CO
2
and temperature were maintained at 720 ppm ± 20 ppm CO
2
and 30°C ± 0.5°C, whereas ambient conditions were maintained at 420
ppm ± 20 ppm CO
2
and 25°C ± 0.5°C. Pepper seedlings or fruits were
infected with each pathogen, and then the disease progress was evaluated
in the growth chambers. According to paired t-test analyzes, incidence of
bacterial wilt and spot were increased on pepper by 24% and 25%, re-
spectively. Intensity of Anthracnose got decreased and while intensity of
Phytophthora blight slightly increased, but the fungal diseases were not
statistically significant, suggesting that bacterial diseases on chili pepper
will likely to be more serious in the future.
5.4
OTHER OBSERVATIONS
• The heavy rainfall from April to October causes heavy soil erosion
and nutrient loss as well as results in manifestation of different types
of insect-pest and diseases and as a result the crop productivity is
reduced to a great extent.
• The long dry spell from November to March results in moisture stress
in many of the horticultural crops and because of this the young or-
chard of
Khasi
mandarin has started declining in entire NEH Region.
