Daylily care - dealing with insects, pests and diseases
Although Daylilies do not require not much care, a proper dose of chemical fertilizer like 6-6-6 or 8-8-8 (NPK) will result in more and larger blooms and vigorous growth. Nitrogenous fertilizer such as calcium ammonium nitrate (CAN) also improves foliage and flower when applied before blooming. Mulching is one of the important operations practiced in Daylilies. It helps to retain soil moisture and to prevent the emergence of weeds.
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If clumps are more than 3-4 years old, they form a large mass and resulting smaller or fewer blooms. Therefore they are divided every 3-4 years during spring or soon after the flowering, when foliage are shortened by two third. Daylilies are also divided from plantlets produced on the flower scape. When flowering is over, removal of old scape and leaves is essential for reblooming and to prevent spread of rust disease.
Insects, pests and diseases
Daylilies plants are generally free from diseases and pests. But some times it is attacked by aphids (Myzus hemerocallis), thrips (Franklinielia hemerocallis), and gall midge (Contarinia quinquenotata (Loew) and root knot nematodes (Meloidogyne incognita) Sometimes other pests which affect these plants are long horned weevils, Japanese beetles, spider mites and grasshoppers. Young foliage of Daylilies is also prone to attack by slug and snail damage.
Thrips may severely injure some species like Hemerocallis citrina, H. multiflora and H. thunbergii. They feed on leaves, flower buds and tips and damaging entire flower clusters. Regular spray of insecticides like Endosulfan or Malathion at the rate 2 ml/ litre can control the incidence of attack.
Aphids produce white flecks on the leaves and also feed on flower buds. In gall midge produces small white maggots in flower buds. Spraying of Malathion or Endosulfan at weekly interval effectively reduce the population of above insect.
Several species of Daylilies are also affected by nematodes. The plants attacked by nematodes show yellowing, drying up of leaves and stunted growth. Application of neem based insecticide or Furadan @ 2 gm per plant effectively controls the nematode populations.
Daylilies can be attacked by several diseases like leaf spot (Cercospora hemerocallis or Heterosporium iridis), leaf streak (Collecephalus hemerocalli), stem rot (Sclerotinia sclerotiorum), spring sickness, crown rot and rust.
In leaf spots, leaves become orange –brown and fungus covers both sides of leaves, destroying chloroplast which adversely affects the productivity of the plant. Incidence of disease increases during rainy season. To control the disease, collect and destroy the infected leaves. Regular spray of Bavistin (0.02 %) or Captan (0.02%) on foliage effectively controls the disease.
In leaf streak disease, necrotic spot and streaking on leaves are found which cause dark brown to whitish colour. Disease is more prevalent at 23-28 o c with high humidity. Although no plant mortality was found. Fungus can be controlled by spray of systemic fungicides.
Fungus attack stems in stem rot disease. To control this disease, soil should be sterilised by chemicals (Formalin) or sun drying and spray with Bavistin (0.02%) or Dithan M-45.
Spring sickness and crown rot diseases are observed in temperate climate where alternate freezing and thawing occurs. It can be prevented by proper mulching. As a preventive measure drenching of soil with Bavistin (0.02%) or Captan (0.02%) is recommended.
A new Daylilies disease i.e. Daylily rust has been reported to attack the leaves. A capsule like growth found on the leaves which contains brown coloured powder like spores. After bursting, Spores spread on neighbouring plants. It can be controlled by regular spray of fungicides and removal of disease infected leaf and clean culture.