Allium flower bulbs - harvesting and storage
Allium flower harvesting and post harvest handling
For cut flower utilization, flowers are harvested when 50%of the florets are ripe. In some cases like A.giganteum, the flower stalk is cut when the florets are almost fully open. Flowers can be stored in water for 2-4 weeks at 0-2°c. Flowers of some species like A.christophii are excellent for drying. Flowers should be dried at a high temperature in a very short time so that they retain their true colour.
Allium Bulb harvesting and storage
Once the flowering period is over, watering is withheld. After the leaves have dried up, bulbs can be lifted, dried & stored. Early harvesting may result in poor quality bulbs whereas delayed harvesting results in splitting and resprouting in field itself. Harvesting is done manually by hand digger. After harvesting, curing is necessary to remove excess moisture from the outer skin. This helps the bulb to become compact and go into dormant stage. Curing also helps to reduce the infection of disease, minimize shrinkage and develop skin colour. Duration of curing largely depends upon the prevailing weather conditions. It takes 7-10 days in shade either with tops or after cutting the tops, leaving 2-5 cm above the bulbs to avoid the sun injury. After curing, bulbs are graded and classified by grading machine or manually. Before storage, doubled, broken, diseased and bulbs having undesirable features are sorted out. Bulbs can be stored at 0.5oc-2.2 o c temperature and 60-70% Relative humidity. Seeds should be harvested at proper maturity and kept in dry, cool place in airtight containers for next season planting.
Guarding against insect, pest and disease
Alliums are mostly attacked by onion flies (Delia antiqua), onion thrips (Thrips tabaci), Allium leaf miner (Napomyza gymnostoma) and stem eelworm (Ditylenchus dipsaci). Maggots of onion flies feed on bulb, roots and leaves & turn the attacked plant yellow. Onion thrips attack on leaves and bulbs. The larvae of leaf miner feed on leaf and bulbs causing these plant parts to become susceptible to bacterial and fungal infections. Crop rotation with non- Allium crops, spray of systemic insecticide like dimethoate (Rogor) @ 1-2 ml / litre helps to control the insect. Stem eelworm causes swollen and softening of leaves. Removal and burning of infected leaves and treatment of soil with chloropyriphos controls the insect population. Some time slugs also feeds on leaves and destroys whole plant. Regularly check the crop and remove it manually.
Diseases affecting Allium flower bulbs
Alliums are susceptible to several fungal diseases such as onion white rot (Sclerotium cepivorum), smut (Urocystis cepulae), rust (Puccinia allii), smudge (Colletotrichum circinans), neck rot (Botrytis allii) and bacterial soft rot (Erwinia spp.).
White rot produces a puffed white fungal growth at the base of bulbs and roots while neck rot shows grey fungal growth on the scales of the neck. All the affected parts become soft and discoloured. Selection of disease free planting materials, removal of infected plants and crop rotation are the preventive measures of these diseases.