Planting Daffodils and how to grow them, resisting pests and diseases
Daffodils contain many chemicals toxic to mammals, including Oxalic acid and other alkaloids. These compounds and their precursors have antimiotic properties. Daffodil plants have been known to be toxic because of their narcotic, purgative and emetic properties when eaten. Their sap is a powerful irritant which can cause rashes on the hands and faces of flower pickers.
Most of the Daffodil flowers are attacked by several pests which include Bulb Flies (Merodon equestries and Eumerus Spp.), the Stem Nematode (Ditylenchus dipsaci), the Root Lesion Nematode (Pratylenchus spp.), the Bulb Mite (Rhizoglyphus Spp.), the Bulb Scale Mite (Steneotarsonemus laticeps, a Tarsonemid mite), Sludge and caterpillars. Bulbs may also be eaten by mice in the field and during storage.
The stem nematode of Daffodil produces symptoms on foliage and Daffodil bulbs. Leaves of affected plants are short pale and often distorted with a few elongated lesions called spickels, which contains nematodes. These often merge to produce necrotic patches and the leaf rots.
Daffodil Bulbs are soft with dull appearance at lifting and when cut across, show characteristic concentric brown rings. During growing season they concentrate in the leaf base and migrate into the soil when bulb dies. Other plants can act as hosts until Daffodil are replanted.
It is essential that stocks regularly inspected when growing, with suspect plants being lifted and destroyed and the land spot treated with nematicide. After lifting, all bulbs should be inspected and soft or suspected bulbs destroyed. Stocks should be given hot water treatment after lifting at 44.4 0 c for 3 hours along with formaldehyde (0.2% commercial formaldehyde).
Daffodil Bulb flies mainly attacks Daffodil bulbs. The adults fly in April- June, and lay single eggs near the surface of the bulbs. These hatch and the larvae enter through the basal plate and fed on the scales till they reach adult stage and pupate the following season.
Some control results from the removal of foliage and the mechanical closure of the hole left above each bulb by the dying foliage. Early lifting of bulbs shortens the duration of exposure of the bulbs to the flies. Damaged bulbs should be removed and destroyed during cleaning. Bulbs can also be dipped in insecticide (Endosulfan or Malathion at 0.05% solution) prior to planting.
Caterpillars generally eat the flowers and leaves. Their larvae severely damage the roots and storage organs. Regular spray and drenches with insecticides controls their population.
Bulb Scale Mites are extremely small pest of Daffodil bulb multiply rapidly throughout the year in the spaces between scales in the neck of the bulbs. Most injury is caused when the bulbs are stored. Another mite which affects the bulbs as a secondary pest is the bulb mite. These are very large to be visible to the naked eye. They increase the amount of original damage, even killing the storage organ, the internal tissue becoming dry and powdery.
Treatment with Systemic Acaricides (Propargite at 0.03% or dicofol at 0.5%) is recommended and repeat applications may be necessary for effective control. Soil sterilization and fumigation of dormant bulbs is effective. Daffodil bulbs suspected of being infected are drenched with dilute Acaricide.
Diseases affecting Daffodil plants
Daffodil is generally affected by several diseases and causes heavy loss to crop .The disease mostly affecting the Daffodil are Basal rot (Fusarium oxysporum f. sp. narcissi), Fire and Smoulder rot caused by sclerotinia polyblastis and s. narcissicola, Leaf scorch (Stagonospora curtissi), White mould (Ramularia vallisumbrosae).
The above incidence disease can be reduced by delaying planting until soil temperatures fall. By dipping bulbs in fungicidal solution (Bavistin 0.02% or Captan 0.02%) for 30 minutes as soon after lifting as possible. Timely spray of fungicides and good hygiene can also control the incidence.
Daffodil is also affected by several virus diseases. Some of which is transmitted by vectors like Aphids, Nematodes and some by contact. In general methods of controlling virus disease is to restrict spread. Virus disease are systemic, all parts of the plant are usually infected except, seed and the apical meristem of the plant.
Rouging of infected plants, avoid mechanical transmission. The isolation of newly planted stock with mother blocks in the field. Planting of bulbs those are virus-free or virus-tested. Timely spray of insecticide to control vectors like aphids is the recommended measure to prevent the spread of disease.