Agriculture Reference
In-Depth Information
are sensitive to salinity. Rise in sea water level due to climate change con-
ditions may adversely affect the cashew plantation. Electrical conductiv-
ity of irrigation water 1.48 dS m
-1
is a threshold tolerance for precocious
cashew during the initial growth (Carneiro et al., 2002). Pot culture studies
on the effect of salinity (1.2 to 20 d Sm
-1
) on cashew seedlings by Valia
and Patil (1997) showed a decrease in plant growth with increased salinity
particularly >14 d Sm
-1
. As salinity increased, all the nutrients (N, P, K, Ca,
Mg, Zn, Fe, Mn and Cu) except S were depleted in leaves and roots. Also,
chlorophyll content and transpiration rate decreased. 'Thane' cyclone with
a very high wind speed created havoc in Cuddalore district of Tamil Nadu
and Pondicherry on 30 December 2011. The entire cashew area of Panruti,
Cuddalore and Kurinjipadi taluks of Cuddalore district were totally dev-
astated. The extent of damage to cashew trees in Vridhachalam taluk was
60-70%due to decrease in the wind speed away from the coast.
Cashew is attacked by around 180 species of insect and noninsect pests
in India resulting in substantial yield loss. Cashew stem and root borers
(CSRB) and tea mosquito bug (TMB) are the major pests of cashew lead-
ing to economic losses. Tea mosquito bug (
Helopeltis antonii
Signoret)
pest and inflorescence blight disease cause considerable damage to ca-
shew. Incidence and severity of both are dependent on climate and weather
factors. Prolonged and unseasonal rains coupled with heavy dew aggra-
vate the incidence of pests and diseases resulting in loss of yield and qual-
ity of cashewnuts. Though cashew flowered profusely during 1995-1996
and 1998-1999 but there was a marked reduction in yield in 1998-1999
in Kannur and Kasaragod districts of Kerala. This could be ascribed to
unprecedented incidence of pests aggravated by heavy dew in February,
1998. Rain received during flowering and harvesting in 2008 increased
the incidence of pests and diseases resulting in very poor yield and quality
(Prasada Rao, 2002).
Of the several foliage insect pests reported to infest cashew, the tea
mosquito bug is of major importance. The production loss from the TMB
alone is estimated to be about 30 percent. Its adults and nymphs feed on
plant sap from the tender shoots, panicles and immature cashewnuts. The
pest causes yield losses ranging from 30-90% depending on the extent of
incidence. The pest population starts building up from September to Oc-
tober and gradually reaches a peak during February. The pest population
is also synchronized with the phenological stages of the crop, which is
also dependent on prevalent weather parameters. Various weather factors
