DISEASE OF FIELD CROPS

1. B.VARSHNI REDDY
111718012007

2. DISEASE NAME:-
 Khaira disease of rice.
Causal agent:-
• This disease occurs due to zinc deficiency.
• It is a non-parasitic and non-infectious disease.

3. SYMPTOMS
 Dusky brown spots on upper leaves of stunted plants.
 Uneven plant growth.
 Increase spikelet sterility in rice.
 Chlorotic midribs particularly near the leaf base of younger
leaves.
 Leaf blade size is reduced.

6. MANAGEMENT
 Grow zinc efficient varieties (oryza nivara,oryza
rufipogon).
 Use fertilizers that generate acidity(example:-replace
some urea with ammonium sulphate).
 Apply organic manure before seeding in nursery or
transplant of rice in main fields.
 Monitor irrigation water quality.
 Broadcast znso4 in nursery seedbed 5days before
pulling out of seedlings.

7.  Dip seedlings or presoak seeds in a 2-4% ZnO
suspension.
 Znso4 25-30kg/ha as soil application at the time of
puddling.
 Mix 5kg znso4+2.5kg slaked lime+1000 liters water and
sprayed it on 10-20days after sowing in nursery.

8. RICE TUNGRO DISEASE
 It is caused by the combinaion of two viruses,which are
transmitted by leafhoppers.it cause leaf
discolouration,reduce tiller number.
 1.Tungro bacilliform virus.
 2.Tungro spherical virus.
 Tungro infects cutivated rice,some wild rice relatves
and other grassy weeds found in rice fields.

9. SYMPTOMS
 Yellowing or orange-yellow discolouration is
noticeable in tungro infected plants.
 Yellowing starts from the tip of the leaf and may
extend to lower parts of the leaf blade.
 Stunted growth,delay flowering, which may delay
maturity.
 Most panicles sterile or partially filled grains.

10.  Yellowing and orange yelow discolouration of leaves.
 Stunted with reduced tillering.

11. PATHOGEN
 Two morphologically unrelated viruses present in
phloem cells. Rice tungro bacilliform virus (RTBV)
bacilliform capsid, circular ds DNA genome and Rice
tungro spherical virus (RTSV) isometric
capsid ss RNA genome

12. PATHOGEN CHARACTERS
 RTBV-dsDNA Bacilliform virus,which cause mild
stunting and yellowing of leaves.
 RTSV-ssRNA virus,which causes only very mild
stunting,without leaf symptoms.

13.  Disease Cycle
Transmission mainly by the leaf hopper
vector Nephotettix virescens Males, females and nymphs
of the insect can transmit the disease.
 Both the particles are transmitted semi-persistently, in
the vector the particles
are noncirculative and nonpropagative. Plants infected
with RTSV alone may be symptomless or exhibit only
mild stunting.

14.  RTBV enhances the symptoms caused by RTSV. RTSV
can be acquired from the infected plant independently
of RTBV, but acquisition of RTBV is dependent on
RTSV which acts as a helper virus.
 The viruses thrive in rice and several weed hosts
which serve as source of inoculum for the next. Ratoon
from infected rice stubble serve as reservoirs of the
virus. Disease incidence depends on rice cultivars,
time of planting, time of infection and presence of
vectors and favorable weather condition.

15.  Management
 Field sanitation, removal of weed hosts of the virus
and vectors.
 Grow disease tolerant cultivars like Pankhari203,
BM66, BM68, Latisail, Ambemohar102, Kamod253,
IR50 and Co45.
 Control the vectors in the nursery by application
of Carbofuran 170 g/cent 10 days after sowing to
control hoppers.

16.  Spray Phosphomidan 500 ml or Monocrotophos 1lit/ha
(2 ml/litre) or Neem oil 3% or NSKE 5% to control the
vector in the main field 15 and 30 days after
transplanting.
 Set up light traps to monitor the vector population.

17. THANK YOU