“Advance Production Technology
of Walnut ”
Pawan Kumar Nagar
M.Sc. Fruit Science
Dept. of Horticulture.
BACA, AAU, ANAND
Overview of Walnut
Botanical Name : Juglance regia
Family : Juglandaceae
Centre of Origin : Central Asia
Chromosome No. : 2n= 32
Sex Form : Monoecious
Infloresccence : Catkin
Growth Curve : Double Sigmoid
Fruit Type : Nut
Edible Part : Cotyledon
Bearing : Axillary old Branches
Propagation : Patch Budding
Type of Dichogamy : Heterostyly
Chilling Req. : 200-800 hours
Nature of fruit : Non-Climecteric
Nature of Plant : Decidous & 10-40 m. tall
Energy : 687 calory
Mode of Pollination : Cross pollination
Mechanism of Poll. : Anemophyllous (Wind)
Butter nut : J. cenaria
Heart nut : J. cordiformis
J. nigra, J. hindsi
Training System : Modified Central leader
Acid Present : Ascorbic & Omega 3 F.A.
Rootstock : Paradox
Dichogamy : Prtoandry
Harvesting : Aug.-Sept.
Protien : 14-20%
Fat : 60-70%
Largest Producer is USA (70% of world)
India stands 8th in production
Wallnut have Allelopathic Effect
Walnut (Juglans sp.) is the most important temperate nut fruit
of the country.
It is grown in jammu and Kasmir, Uttar Pradesh and Himachal
There are no regular orchards of walnuts in country because
the existing planting are generally of seedling origin.
The seedling trees attain giant size and start bearing nuts of
variable size and shape after 10-15 years,
whereas vegetatively propagated plants are true to type and
produce almost uniform sized nuts after 4-5 years. They
remain within manageable size.
But the major constraint is low success in vegetative
propagation. Limited availability of scion material from desired
tree results in very few vegetatively propagated plants.
Most valuable Exchange Earning nut crop.
Species and classification
Sect. Juglans. Leaves large (20-45 cm) with 5-9 broad leaflets, hairless , margins entire. Wood hard. Southeast
Europe to central Asia.
Juglans regia L. (J. duclouxiana Dode, J. fallax Dode, J. orientis Dode) - Persian Walnut, Carpathian, or
Juglans sigillata Dode - Iron Walnut (doubtfully distinct from J. regia)
Sect. Rhysocaryon. Leaves large (20-50 cm) with 11-23 slender leaflets, finely pubescent, margins serrated. Wood
hard. North America, South America.
Juglans australis Griseb. (J. boliviana Dode) - Argentine Walnut
Juglans brasiliensis Dode - Brazilian Walnut
Juglans californica S.Wats. - California Walnut
Juglans hindsii (Jepson) R.E.Smith - Hinds' Walnut
Juglans hirsuta Manning - Nuevo Leon Walnut
Juglans jamaicensis C.DC. (J. insularis Griseb.) - West Indies Walnut
Juglans major (Torrey) Heller (J. arizonica Dode, J. elaeopyron Dode, J. torreyi Dode) - Arizona Walnut
Juglans major var. glabrata Manning
Juglans microcarpa Berlandier (J. rupestris Engelm.) - Texas Walnut or Little Walnut
Juglans microcarpa var. stewartii (Johnston) Manning
Juglans mollis Engelm. - Mexican Walnut
Juglans neotropica Diels (J. honorei Dode) - Andean Walnut
Juglans nigra L. - Black Walnut
Juglans olanchana Standl. & L.O.Williams -
Juglans peruviana Dode - Peruvian Walnut
Juglans soratensis Manning -
Juglans steyermarkii Manning - Guatemalan Walnut
Juglans venezuelensis Manning - Venezuela Walnut
Sect. Cardiocaryon. Leaves very large (40-90 cm) with 11-19 broad leaflets, softly downy, margins serrated. Wood
soft. Northeast Asia, eastern North America.
Juglans ailantifolia Carr. (J. cordiformis Maxim., J. sieboldiana Maxim.) - Japanese Walnut
Juglans cinerea L. - Butternut
Juglans mandshurica Maxim. (J. cathayensis Dode, J. formosana Hayata, J. hopeiensis Dode, J. stenocarpa
Maxim.) - Manchurian Walnut or Chinese Walnut.
Excellent source of Proteins (14-20%)
Excellent source of Fats (60-70%)
Rich in Omega 3, vitamin B and E, fibres and trace elements;
High energetic value;
Highly recommended to athletes;
Immature fruits are rich in Ascorbic acid.
There’s already a Canadian and world market for Walnuts
Walnut have high Anti-oxidant content(vitamin-E)
Sl.No Content Amount/100g
1 Water 3.5 %
2 Protein 14.8 g
3 Fat 64.0 g
4 Carbohydrate 15.8 g
5 Fibre 2.1 g
6 Ash 1.9 g
7 Calcium 99 mg
8 Phosphorus 380 mg
9 Iron 3.1 mg
10 Sodium 2 mg
11 Potassium 450 mg
12 Magnesium 131 mg
13 Vitamin A 30 I.U *
14 Thiamine 0.33 mg
15 Riboflavin 0.13 mg
16 Niacin 0.9 mg
17 Vitamin C 2 mg
USES AND COMPOSITION
Walnut kernel (the edible portion) is very rich in protein, fat
and minerals and is a concentrated source of energy.
The walnut kernels are used for dessert purposes in
confectionery and for extraction of oil and as a dry fruit.
Immature fruits are used for making pickles, chutneys,
marmalades, juice and syrups.
Walnut oil is used for edible purposes, artist oil colours,
varnishes and soap making.
Walnut shell flour is used as ingredient in plastic pillers,
battery cases, moulding resin forms, industrial tile and as
Walnut timber is used for furniture, carving and making butts
highly sensitive to the extremes of winter and summer
temperatures as well as to its duration.
climate which is free from frost in spring and from extreme
beat in summer.
A temperature of even 2 or 3 degree below freezing point (0oC)
kills leaves, shoots and flowers and thus resulting into a crop
High temperature of about 38°C causes sun-burning of hulls
and shriveling of kernels resulting sometimes in empty nuts.
An annual rainfall of about 80 cm is considered sufficient for
the cultivation of walnut which can be supplemented drier
regions with irrigations, particularly for young plants.
A well drained, deep sill loam soil containing an abundance of
organic matter is the most suitable for walnut cultivation.
Soil analysis of top soil and sub-soil is also essential as the
walnut requires a fertile and well drained top soil and the
sub-soil should be free from solid rock, impervious clay or
gravel layers which restrict root growth.
A soil depth of 2-3 metres give the best results, because
walnut roots penetrate up to a depth of about three metres.
It requires a soil pH of neutral range i.e. 6 to 7.
All walnut trees in India are of seedling origin, thus no
standard named varieties exist. However, a large number of
cultivars have been evolved in the USA which is the main
walnut exporting country of tile world. Description of some
important varieties are given here.
It is one of the most popular commercial cultivars of
California. It is a selection from a seedling. The nuts are large
with broad flat base and pointed tip. The shell is light
coloured, thin and seals well. The variety is tolerant to codling
moth and blight disease.
It is tile second leading cultivar of California which originated
as a seedling. Nut is medium to small in size with a good seal.
Trees are moderately vigorous, round in shape and require
heavy pruning to maintain vigour.
It is an old and leading cultivar of France. Nut is small, good
shell seal and kernel is light. in colour. Tree is large and
upright in nature and is known for its late bud break thus
escaping injury from frost during late spring.
It was evolved from a cross of Payne X PI 159568. It is heavy
yielding and well adapted to warm conditions. The tree is very
vigorous and gives poor yield on very fertile soils. The kernel is
light in colour and good in quality. It is susceptible to codling
moth and blight disease.
It is a high yielding, early bearing cultivar which requires
heavy pruning to keep the tree vigorous. Kernel is of high
quality, good in flavour and light tan in colour. This variety is
unsuitable for high rainfall areas due to blight problem.
Walnut can be propagated either by seed or by vegetative
methods. Both of these methods are described here.
1. Seed propagation- Healthy and disease free seeds should be
selected for sowing. They may be sown in lines 50 cm apart
and the seed to seed distance should be kept at 25 cm.
Sowing is done during mid-November to mid-January
depending on the altitude and temperature. it is advisable
to avoid propagation by seed because the plants which are
grown by this method take a very long time (10 to 12 years)
to begin fruiting and the plant characteristics may also not
be true to type.
2. Vegetative propagation
Walnut can be propagated vegetatively by grafting, budding
Tongue or whip grafting, cleft and veneer grafting during February and early March have given good
results. Epicotyl grafting has also given encouraging success in tile propagation of walnut.
The best period for grafting is January -February. For propagating tile plants through veneer grafting,
5-6 month old scion wood of 15 cm is grafted on the rootstock of same thickness. The selected scion
wood should be defoliated 15 days prior to its detachment from the scion cultivars. The optimum
time for veneer grafting under mid -hill condition is July -August. One year old seedlings of hard
shelled walnut or black walnut can be used as rootstock. Scion for tongue grafting should always be
selected from the tree which has already started fruiting.
2.Patch budding is generally practiced to propagate walnut
plants vegetatively. The best period for budding is May -June.
Scion should always be selected from the tree which has already
PLANTING & IRRIGATION
Square system & Pits of 1.25 X 1.25 x 1.25 m size at a
distance of 10 X 10 m should be dug during September. The
pits should be filled up with orchard soil mixed with 50 kg
well rotten FYM, 150 g Aldrin dust, 150 g urea, 500 g each of
superphosphate and MOP. Walnut plantating in Dec.-Jan.
The plant should be well fixed in the soil and the adjoining
portion of scion and stock union should be at least 15 cm
above the ground surface. Watering should be done soon after
plantation. To protect the plant from collar rot it should be
treated with Dithane Z- 78 before planting.
Watering is very essential for the establishment of grafts and
young plants.. When the trees start bearing, irrigation should
be given from the time of fruit set till its maturity to reduce
the fruit drop and for better filling of nuts. When the trees are
grown under rainfed conditions and common irrigation
systems followed are flood, furrow, sprinkler and drip
Persian Walnut Planting Plan
Tree spacing 28' x 28' x 40' in a triangular pattern. Area = 1.1 Acres or 0.45 ha.
Gl, G2 and G3 are 3 different grafted cultivars totaling 60 trees
FUTURE FOLLOW UP
When trees crowd, remove the 30 trees in the even numbered walnut rows. Good trees can be tree
spaded into a new planting that will begin to bear in a few short years. Gl should be a prolific variety
like Lake to maximize the early year production
TRAINING & PRUNING
Modified central leader system is most ideal for training since
it provides very good strength to its framework.
Trees should be trained on a single stem up to 1–2m, on which
5–6 scaffold branches should be retained at almost uniform
Excess buds should be pinched during first year. Pruning is
not being practiced in our country, as almost entire plantation
is of seedling origin, attaining giant size which makes pruning
in later years almost impossible.
However with grafted plants, pruning is practicable which can
help increase the productivity and improve the quality.
Trees of seedling origin receive some kind of pruning while
harvesting by thrashing the limbs with wooden poles.
It is however a crude method which needs to be modified.
MANURES & FERTILIZERS
Use the following guide below as a indicative amount of NPK for
in the absent of plant and soil nutrients analysis information:
Year N Dose (g/tree) Location: circle around the tree (m)
1 100 0.5
2 200 1.0
3 300 1.5
4 400 2.0
5-7 500 2.5
7-9 600 3.0
>10 900 3.0
• In the first five years, place small amounts (about 100 g) of P
and K per tree.
From fifth year up to full production, apply 40-80 kg/ha of P
and 60-100kg/ha of K based on soil fertility and plant vigour.
Self – fertile, but dichogamous Pollen release from male
flowers dosen’t coincide with bloom of female flowers Pollinizer
Age to commercial bearing 6-10 yrs
Tree density at full production 30-50 trees/ acre
Peaches often interplanted for first 10-15 years
A green husk surrounds the nut of
the English Walnut. The husk
naturally splits at the time of
ripening to release the nut
Mature walnut fruit closeup English walnut leaf
Inside of a Persian Walnut nut with green outer layer
visible in the top left corner
The shell of the English walnut is light brown, hard, and bumpy. It is
roughly oval and tapers at the bottom. The shell has an vertical seam
dividing it into two halves.
Walnut meats have a lobbed and wrinkled appearance. The outside is
golden brown and the inside white to light brown. Inside each shell are
two nuts, separated by a thin, paper-like layer. Each nut meat
resembles a butterfly or wings, with two flared lobes joined by a smaller
centre section. Walnuts can be confused with pecans, but pecans look
more like a brain than wings
English walnut trees grow 40 to 60 feet in height and width and have an rounded to
spreading shape to their canopy.
English walnut leaves are compound and arranged alternately along the stem
The leaf is composed of 5 to 9 leaflets, each reaching a length of 2 to 5 inches.
English walnut and Black walnut differ in the number of leaflets, the shape of the
leaflets, and the leaflet margin. black walnut leaves have a greater number of
leaflets (15-23) than English walnuts (5-9). English walnut leaflets have more oval
shaped leaves while black walnut leaves are generally smaller and narrower in
shape. Black Walnut leaflets have toothed margins while English walnut leaflet
margins are entire.
English walnut and Butternut have the same general leaf shape. They differ in the number of
leaflets, butternut has 11-19 leaflets, while English walnut has only 5-9. Also, butternut has a
toothed margin, while the leaf margin of the English walnut is entire.
Black walnut fruit is usually between two and three inches in diameter. The husk (shown
here) is rough and light green in color and forms the outer layer of protection for the nut
Black walnuts grow in clusters amidst the pinnately compound leaves
Walnuts are usually harvested when hull colour changes from
green to yellowish with cracks or when splitting starts at suture
from pedicel end. Nuts should be harvested at PTB stage (when
packing tissue turns brown). For better nut recovery, the
orchard floor should be cleaned and tarpaulin or polythene
sheets may be spread on the floor beneath trees prior to
knocking of the nuts. After harvesting, nuts should be properly
dehulled, washed and dried. In case nuts are not dried properly
there is every apprehension of mould development which
impairs the quality of the fruit.
In Himachal Pradesh harvesting commences from August and
extends up to last week of September, whereas in Kashmir
walnuts are harvested in September.
HARVESTING AND POST HARVESTMANAGEMENT
The shell is brown and wrinkled in appearance and and is the second layer of
protection for the nut. The nut is found inside the shell.
Black walnut trees are very large, ranging from 50 to 75 feet in height and width.
Walnut shoot cut longitudinally to show chambered pith. Scale in mm
Black walnut kernels are often used in the manufacturing of ice cream, commercial
baking, and candy making
1. Anthracnose FUNGUS (Gnomonia leptostyla)
Brown to black lesions on leaves, petioles, shoots and/or husks which
fade toward the center and may be surrounded by a chlorotic halo; spots
may coalesce to form large necrotic patches, usually located close to leaf
margins; lesions on shoots, petioles and leaf midribs become elongated
Disease affects English walnut and is widespread in Europe; disease is
also known to occur in the Pacific Northwest of the United States
Control of anthracnose in pistachio relies on the application of
appropriate fungicide sprays; cultural practices can help to reduce the
severity of the disease and include: removing leaf debris from around
plants, avoiding wetting foliage when irrigating, spacing trees adequately
to increase air circulation and applications of nitrogen fertilizer in Spring
to delay leaf maturity and reduce the development of lesions
2. Armillaria root rot (Oak root fungus) FUNGUS (Armillaria mellea)
SYMPTOMS- Small, discolored leaves which drop early; death of branches;
death of plant; clusters of honey-colored mushrooms may sprout at base of
COMMENTS- Fungus survives on dead roots in soil
MANAGEMENT- Armillaria root rot cannot be effectively controlled once it has
become established in an orchard; diseased or dead plants should be uprooted
and removed; planting resistant rootstocks is the most effective method of
preventing the disease
3. Blackline disease VIRUS Cherry leaf roll virus (CLRV-W)
SYMPTOMS- Gradual reduction in tree vigor; leaves are yellow and drooping;
defoliation occurs prematurely and is followed by dieback of terminal shoots;
small holes or cracks may be present at the graft union and underlying tissue
may be dis colored
COMMENTS- Virus may be introduced from infected graft wood or infected
MANAGEMENT-Introduction of the disease to un-infested areas can be
prevented by using virus-free graft and bud wood from English walnut; in areas
where the disease is uncommon, immediate removal of trees identified as being
infected can prevent spread.
3.Crown gall BACTERIUM (Agrobacterium tumefaciens)
Galls of various sizes on roots and root crown below the soil
line; galls may occasionally grow on the trunk; galls are initially
light colored bulges which grow larger and darken; galls may be
soft and spongy or hard; if galling is severe and girdles the
trunk then young trees are weakened due to constricted
vascular tissue; trees may be stunted and rarely die
The bacterium enters host plants through wounds and causes
plant cells to proliferate and cells to be undifferentiated, leading
to the formation of a gall
Only plant disease-free nursery stock; plant trees in well-
draining soils; avoid wounding the plants as much as possible;
fresh wounds can be treated with a biocontrol agent
(Agrobacterium tumefaciensK84), if available, to prevent the
4. Phytophthora root and crown rot OOMYCETE(Phytophthora spp.)
Slow growing trees with reduced vigor; leaves of tree turning yellow
and wilting; shoots and branches dying back; if tree is girdled at the
trunk or root crown then death occurs, usually within one growing
season; infected tree roots are necrotic and discolored black or brown;
most roots eventually die; trees with crown rot may exhibit cankers of
the root crown which extend above the soil line; cankers are visible as
discolored bark and possess a zonate appearance when the bark is
Disease emergence favored by water saturated soils; disease is usually
introduced to orchards through contaminated soil, water and plants
Control should focus on minimizing soil wetness and saturation by
planting trees in well-draining soils; drainage can be improved by
levelling soil or installing drainage systems; avoid wetting tree trunks
when irrigating; ensure graft union is several centimeters above the
soil line when planting trees
5. Walnut blight BACTERIUM(Xanthomonas campestris)
Small, water-soaked spots on immature fruit which darken and rapidly
enlarge; bacterial exudate may be present during wet weather; if infection
occurs prior to shell hardening then the kernels shrivel; infections which
occur later may cause kernel discoloration but the fungus does not usually
invade the kernel; catkins which become infected are are dark and shrivelled;
new shoots may also be attacked and lesions may girdle the stem, killing the
shoot above; lesions may form on tree bark and may also extend into the pith
causing cankers to form; lesions on leaves are brown with a green-yellow
perimeter; leaf lesions may coalesce to form large necrotic areas
Bacteria overwinter in dormant buds; following bud break the following year,
bacteria infect surrounding leaves and young fruit; emergence of walnut blight
is favored by periods of wet weather
The primary method of controlling walnut blight is the application of copper
containing bactericides such as Bordeaux mixture; bactericides should be
applied weekly to protect new growth during periods of wet weather
6. Powdery mildew FUNGUS (Phyllactinia guttata)
Small, powdery white spots on leaves and fruit; spots
spread to cover entire leaf; small black fungal fruiting
bodies may be visible in the white growth; young leaflets
may crinkle as they mature
Disease emergence favored by moderate temperature,
poor air circulation around plant and shady conditions
Disease is not severe enough on walnut to warrant
1. WALNUT HUSK FLY- (Rhagoletis completa), infests walnuts in most
California walnut-growing areas. It feeds on black walnut and on all varieties
of English walnut, but some early maturing varieties can escape infestations
in most years.
IDENTIFICATION- The walnut husk fly is about the size of a housefly and
very colorful. It has a yellow spot just below the areas where the wings are
attached and iridescent, greenish eyes. The wings have three prominent dark
bands, one of which extends around the wing to form a V-shape (Fig. 1). The
banded wings distinguish it from other flies found in the walnut orchard.
DAMAGE The primary damage from the husk fly is nutshell staining, which
is a problem in commercial orchards where nuts are grown for in-shell sale;
however, this can be tolerated in backyard situations. Feeding by the husk fly
maggots also causes the damaged husks to stick to the shell, making them
difficult to remove. An early season husk fly infestation (June to mid-August)
can result in shriveled, moldy kernels. MANAGEMENT Most home orchardists
ignore the walnut husk fly, because generally it doesn’t affect the nutmeats.
Since the husks can be difficult to remove, home orchardists can place the
damaged nuts in a damp burlap bag for a few days before attempting to
remove the hull. Be sure to dispose of infested husks in a tightly sealed bag.