Diseases and Management of Crops under Protected Cultivation

(Diseases and Management of Crops under Protected Cultivation)
size was found ideal for primary nursery. After making 6 holes in bottom of trays to drain out
excess water, trays are filled with sterilized potting mixture (One part fertile soil + one part sand +
one part FYM) and trays are kept at 1.5 feet height from the ground on the bricks or on cement
platform to check the contamination. After leveling the mixture up to top level of trays seeds are
sown at depth of 1- 1.5 cm with spacing 2.5 to 3.0cm in the row and after sowing light shower
irrigation should be done with a water can. The germination starts within 20-25 days after seed
sowing depending upon the rootstocks. Citrus seeds usually germinate at a soil temperature
above 55 0 F. The optimum temperature is between 80 and 90 o F. It is necessary to protect the
primary nursery with some type of shelter. Both intense sun and wind may cause emerging
seedlings to burn. The shade net (50 % shade) was found ideal for citrus seedlings. Irrigation of
seedlings is most critical aspect. Germinating seeds are quickly killed by drought and on other
hand, excessive moisture favours the development of damping off fungus. Therefore, frequent and
light watering is required for newly planted seed beds.
Transplanting of seedling in secondary nursery
Seedling when 4 to 6” tall having 8 to 10 leaves are transplanted to black polythene bag of 12” to
6” size having 3-4 holes at the bottom to drain out excess water. The polythene bags are filled with
sterilized potting mixture and arranged in shade net. To ensure uniform nucellar seedlings, discard
of markedly smaller or too taller ones at the time of transplanting. Seedlings from primary nursery
(Trays) should be uprooted with fork carefully to minimize root damage. The hook-necked bent or
twisted taproot seedlings should be avoided. Selected seedling should be treated with Ridomil
(2.75g /litre water) solution before transplanting to check the contamination at the time of
transplanting. The seedlings are transplanted in the month of July-Aug after commencement of
monsoon. The holes in which the seedlings are to be planted are usually made by stick. The roots
of the seedling are then placed in the opening and pressing the soil firmly around the seedling to
make contact of soil with roots for quick and better establishment. Irrigation should follow the
planting of seedlings. In the beginning water should be applied frequently to overcome the shock
of transplanting. The nursery must be kept free from weeds at all times. The side shoots should be
removed regularly to develop single straight stem. Frequent and light irrigation should be given as
per need taking care to avoid water stagnation in polythene bags. If such bags found excess water
may drain out through making the new holes in polythene bags.
Selection of mother plants and bud wood:
Selection of mother plants for bud wood is the most critical parts of production of disease-free
planting material. Since plant productivity, longevity, fruit quality and most important free from
diseases all depend on types of mother plants. Therefore mother plants should be selected from
authentic sources with known pedigree in respect to health, vigor, regular bearing and high yield
with good quality fruit. Selected plants should be indexed against diseases (viruses and Greening
bacterium) and only disease free plants should be used as bud source. Such disease-free plants
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