Strawberry
Strawberry
(Fragaria sp.) is a native of temperate regions, but varieties are available which can be
cultivated in sub. Tropical climate. In India it is generally cultivated in the hills. Its
main centres of cultivation are Nainital (district) and Dehradun in Uttar Pradesh,
Mahabaleshwar (Maharashtra), Kashmir Valley, Bangalore and Kalimpong (West Bengal). In
recent years, strawberry is being cultivated successfully in plains of Maharashtra around
Pune,Nashik and Sangali towns. The strawberry is the most widely adapted of the small
fruits. Strawberries are grown throughout Europe, in every state of the United States, as
well as in Canada and South America. The wide variation in climates within these regions
and the wide adaptation of the strawberry plant permit harvesting and marketing, the fruit
during greater part of the year.
Importance:
Strawberry is a
delicious fruit taken fresh in several ways. It also makes excellent ice cream and Jam on
account of its rich aroma, and is also a good source of vitamin C. It is a soft and a
highly perishable fruit, often shipped in frozen condition in Western countries.
Climate:
Strawberry thrives
best in temperate climate. It is a short day plant which requires exposure to about 10
days of less than 8 hours sunshine for initiation of flowering. In winter, the plants do
not make any growth and remain dormant. The exposure to low temperature during this period
helps in breaking dormancy of the plant. In spring when the days become longer and the
temperature rises. The plants resume growth and begin flowering. The varieties grown in
milder sub. Tropical climate do not require chilling and continue to make some growth
during winter.
From the standpoint of
response to length of the light period, strawberries are placed in two groups: (1)
varieties that develop flower buds during both long and short light periods, the
everbearing varieties and (2) varieties that develop flower buds during the short light
periods only, most commercial varieties.
Soil requirement:
Strawberry requires a
well-drained medium loam soil, rich in organic matter. The soil should be slightly acidic
with pH from 5.7 to 6.5. At higher pH root formation is poor. The presence of excessive
calcium in the soil causes yellowing of the leaves. In light soils and in those rich in
organic matter, runner formation is better. Strawberry should not be cultivated in the
same land for a number of years. It is preferable to plant it in green manured field.
Alkaline soils and soils infected with nematodes should be avoided.
Varieties:
A large number of
varieties are available. For the hilly areas, varieties Royal Sovereign, Srinagar and
Dilpasand are suitable. Some of the introductions from California, such as Torrey, Toiga
and Solana may prove even more successful. The variety found successful in Bangalore has
been named Bangalore and which has performed well at Mahabaleshwar also. For the north
Indian plains, Pusa Early Dwarf which has dwarf plants, large firm wedge-shaped fruits,
has been recommended. Another variety with rich aroma but softer fruits is Katrain Sweet.
Some of the varieties found successful in warmer parts of the U.S.A. are: Premier
Florida-90, Missionary, Blackmore,Klonmore & Klondike. Some of these may prove
successful for cultivation in Indian plains.
Propagation:
Propagation is done by
means of runners that are formed after the blooming season. The plants may be allowed to
set as many runners as possible but not allowed to set any fruits. All the plants with
good root system should be utilised to set a new plantation. Given the best attention and
care, a single plant usually produces 12 to 18 runners.
Planting:
The land for
strawberry planting should be thoroughly prepared by deep ploughing followed by harrowing.
Liberal quantities of organic manure should be incorporated in the soil before plating.
Strawberry can be planted on flat beds, in the form of hill rows or matted rows, or it can
be planted on raised beds. In irrigated areas, plantings on ridges is advised. In
Mahabaleshwar, the usual practice is to plant on raised beds 4 x 3 meters or 4 x 4 meters.
The planting distance should be 45 cm from plant to plant and 60 to 75 cm.from row to row.
In the hills, Transplanting is done in March-April, September-October, but in the plains,
the months of January-February may be utilised for this purpose. At Mahabaleshwar normally
strawberry is planted during November-December.
The plants should be
set in the soil with their roots going straight-down. The soil around the plant should be
firmly packed to exclude air. The growing point of the plant should be just above the soil
surface. During planting, the plants should not be allowed to dry out and should be
irrigated immediately after planting.
Care Of Young
Plantation:
The roots of
strawberry plants spread out close to the surface. Therefore, the soil should be
well-supplied with moisture, and hoeing should be done lightly and young plantation be
kept weed free.
Special Horticultural
Practices:
In cold climate the
soil is covered with a mulch in winter to protect the roots from cold injury. The mulch
keeps the fruits free from soil, reduces decay of fruits, conserves soil moisture, lowers
soil temperature in hot weather, protects flowers from frost in mild climates and protects
plants from freezing injury in cold climates. Several kinds of mulches are used, but the
commonest one is straw mulch. The name strawberry has been derived from this fact. Black
alkathine mulch is also used to cover the soil. It saves irrigation water, prevents the
growth of weeds and keep the soil temperature high.
Irrigation:
Since strawberry is
relatively shallow-rooted, it is susceptible to conditions of drought. Planting early in
autumn allows the plants to make good vegetative growth before the onset of winter.
However, in this case it is necessary to ensure that newly planted runners are irrigated
frequently after planting, otherwise the mortality of the plants becomes high. During
September and October, irrigation should be given twice a week if there is no rain. It may
be reduced to weekly intervals during November. In December and January, irrigation may be
given once every fortnight. When fruiting starts, the irrigation frequency may should
again be increased. At this stage frequent irrigation gives larger fruits.
Nutrition:
Strawberry requires
moderate amounts of nitrogen. Addition of organic matter to the soil, in the form of 50
tons of Farm Yard manure per hectare is highly desirable. It improves the water holding
capacity of the soil and also gives better runner formation. Farm yard manure may be
supplemented by chemical fertilizers to make up the total quantity of nitrogen from 84 to
112 kg per hectare, Phosphorus 56 to 84 kg per hectare, and Potash 56 to 112 kg per
hectare. The Phosphatic fertilizer should be incorporated into the soil before plantings.
The nitrogenous fertilizer be applied in Two doses (Three weeks after planting and again
at the time of flowering) and potash at the time of flowering only. Application of
adequate amounts of nitrogen gives higher yield of early berries.
Plant Protection:
Red spider mites and
cutworms are important pests of strawberry. The mites can be controlled with 0.05 per cent
Monocrotophos + 0.25 per cent wetable sulphur. The cut worms can be controlled by dusting
the soil before planting with 5 per cent chloradane or Heptachlor dust at the rate of 50
kg per hectare and mixing it thoroughly in the soil by cultivator.
The two commonest
diseases of strawberry are red stele, caused by the fungus Phytophthora fragariae and
black root rot. The remedy for the former lies by growing resistant varieties like
stelemaster and for the latter to maintain the vigour of the plants and rotate strawberry
with other crops like legume vegetables (beans, peas etc). Strawberry also suffers from
virus diseases known as yellow edge, crinkle and dwarf. Raising of strawberry nursery in
the hills helps to check these. Strawberry also throws some chlorotic plants, which result
from genetic segregation. These should not be confused with virus affected plants and
should be rogued out.
Harvesting and Yield:
The fruit ripens
during late February to April in the plains and during May and June at high elevations
like Mahabaleshwar, Nainital and Kashmir. For local market the fruit should be harvested
when fully ripe, but for transport to distant markets, it should be harvested when still
firm and before colour has developed fully all over the fruit. Harvesting should be done
preferably daily. Since fruit is highly perishable, it is packed in flat shallow
containers of various types (card board, bamboo, paper trays etc.) with one or two layers
of fruits. Harvesting should be done early in the morning in dry conditions. Washing the
fruit bruises it and spoils its lustre.
The yield varies
according to season and locality. A yield of 20 to 25 tons per hectare is excellent,
though yields upto 50 tons per hectare have been reported under ideal conditions.
Post Harvest Handling
And Marketing:
Strawberries are
highly perishable and hence a great deal of care in harvesting and handling as well as its
marketing also requires to be organised carefully. Usually the fruit is picked in the
early morning and sent to the market in the afternoon of the same day or is picked in the
late afternoon, stored overnight in a cool place, and sent to market the following
morning. |