AAU-Citrus and Plantation Crops Research Station, Tinsukia

#CRS, Tinsukia has 154 numbers of citrus germplasm; both primary and
secondary.
#The nursery of CRS has been accredited as III (3*) star Nursery by National
Horticulture Board, GOI.
#CRS has been
multiplying and supplying citrus quality planting material to various states of
NE region viz., Mizoram, Meghalaya, Nagaland, Arunachal Pradesh
including Assam.
#Tinsukia district has
already been declared as orange
district, in a joint effort of Citrus Research Station, AAU and District
Administration, Tinsukia with a vision to increase the acreage, production
& productivity of Khasi mandarin and encourage orange export with the
benefit of income generation & livelihood in rural areas of the district.

#Under the supervision of
CRS, the Assam lemon farmers were guided and assisted and linked with IPR cell
of AAU, Jorhat and Dept. of Horticulture, AAU, Jorhat applying for Geographical Indication (GI) for Assam
lemon and recently, GI for Assam lemon is announced for the benefits of the
farmers. 

Production Technology:

Ø  Rejuvenation package for
declining Khasi mandarin orchards: The technology generated under the Tinsukia centre
of ICAR-AICRP (Fruits) have been utilized for developing a “Package of
Practices for Rejuvenation of Declining Khasi mandarin orchards”; which was
validated on farm and was successful in rejuvenating the declining Khasi
mandarin orchards in Assam with special reference to Upper Brahmaputra Valley
Zone (UBVZ). This technology generated under ICAR-AICRP (Fruits) has been
borrowed by other Northeastern states also.

Ø  Stage wise requirement of
nutrients in Khasi mandarin: Nutrient
application of N: P₂O₅: K₂O at 30:40:10, 30:35:10,
20:25:30, 10:0:25 and 10:0:25 per cent of RDF during March-April, May-June,
July-August, September-October and November-December was found to be effective
in improving the yield and quality of Khasi mandarin.

Ø  Integrated nutrient management
in Khasi mandarin: Application
of 75% of Recommended Dose of Fertilizer + VAM (500 g/plant) + PSB (100
g/plant) + Azospirillum, (100
g/plant) + T. harzianum (100 g/plant)
in two splits were found to be effective in improving the yield and quality of
Khasi mandarin.

Ø  Fertigation scheduling in
Khasi mandarin: Irrigation
schedule at 80-90% Evaporation Replenishment (ER) with 70-80% RDF fertigation
through drip irrigation system during the flowering to fruit development in
summer months (January-June) with water stress in December is recommended for
better plant growth, higher yield and quality fruits.

Crop Protection Technology:

a.     Pest
management:

Ø  Management of lemon
butterfly, Papilio spp. in citrus: Foliar application of Bacillus thuringiensis
(0.1%) or Beauveria bassiana @ 4 X 10⁶cfu/ml (0.1%) at the
appearance of the larvae on leaves is recommended for the management of lemon
butterfly.

Ø  Bio-rational management
of Citrus psylla, Diaphorina citrii:
Foliar application of abamectin 1.9 EC @0.007% or novaluran 10EC @ 0.005% twice
at 15 days interval during flushing period, with the appearance of nymphs on
twigs, is recommended against citrus psylla.

Ø  IPM
module for Citrus Insect Pest Management: Trunk
Borer and Bark eating caterpillars - Smearing of tree trunk up to 1m of height
from the base with 50 ml Dimethoate + 2 kg lime/ 10 liters of water during
March. For Citrus butterfly, aphids and citrus psylla and other crawling insect
pests - Spray with 2% Petroleum oil and tie with paddy straw at a height of one
meter around the tree trunk during April have been recommended.

Ø  Spray schedules against
leaf miner in Citrus (Nursery/young orchards): Foliar application of neem formulation 10000 ppm @ 5
ml/l followed by spinosad (0.015%) or thiamethoxam (0.008%) at 7 days interval
during the new flushing period effectively manage citrus leaf miner up to 14
days after spraying.

Ø  New acaricides for mites’
management in Citrus: The
application of Propargite 57 EC @ 1 ml/l or Spiromesfen 240 SC @ 0.39 ml/l at
15 days interval starting from 15 days after fruit initiation (two sprays
during May- June or August-September) reduces mite damage on leaves and fruits
as well as enhances number of marketable fruits in citrus.

Ø  Use
of repellents against fruit sucking moth in Citrus: The
application of neem oil 1% @ 10 ml/l at color breaking stage reduced the damage
of fruit sucking moth and enhance the number of marketable fruits in citrus.

b.    
Disease
management:

Ø  Management of fruit drop due to Pre harvest stem end rot of Khasi
mandarin: Four sprays of Trifloxystrobin
0.1% (1 g in 1 ltr of water) at monthly intervals from May
i.e. after fruit set to control fruit drop due to preharvest stem end rot.

Ø  Twig blight
of Khasi mandarin:  Twig blight or wither tip or
dry-up twigs can be effectively managed by pruning in the month of
January/February followed by two sprays of Azoxystrobin 23% SC @ 0.1% and there
after 2 sprays of Copper oxychloride 0.3% (3g in 1 ltr of water) at monthly
interval.

Ø  Integrated management of Phytophthora root
rot of Mandarin: Application of Bordeaux
paste on trunk with soil application of Trichoderma
harzianum (100 g/plant) + Trichoderma
viride (100g/plant) Pseudomonas
fluorescens (100g/plant) followed by
Fosetyl (Aliette 0.2 %) spraying was the most effective for management of Phytophthora root rot of Khasi mandarin.

Ø  Management of Citrus canker bacteria: Five numbers of foliar spray of copper oxychloride 50%WP
(0.3% i.e., 3 g/ltr) + Streptocycline100 ppm (i.e., 1 g/10 ltr)
and NSKE 5% at 30 days interval starting from 2^nd fortnight of June
is effective in management of Citrus canker of Assam lemon.

Ø  Eco-friendly management of Phytophthora
root rot and gummosis in mandarin: Application of Bordeaux paste (1:1:10) on tree trunk as pre-monsoon (in
the month of May) and post monsoon (in October) with foliar spray (two sprays-
pre-monsoon and post monsoon) of Potassium phosphonate @ 0.3% is recommended
for integrated management of Phytophthora root rot and gummosis of
mandarin.

Ø  Integrated
Management of Citrus Greening Disease: Soil application
of 50% more than recommended dose of Phosphorus (along with recommended dose of
nitrogen and potash), two sprays of Tetracycline hydrochloride @ 6 g/ 10 lit of
water at an interval of 45 days during the month of October to December and 15
days later ZnSO₄ (200 g/plant) is effective for management of
greening disease of Citrus.