Sunflower (Helianthus annuus L.)
1. Sucking pest, Amrasca biguttula biguttula Ishida (Cicadellidae: Homoptera)
Distribution: This pest is of economic importance in Maharashtra, Tamil Nadu and Karnataka causing crop loss up to 46 %. Though it may appear on the crop round the year, it is serious during certain months at different places. Summer crops are likely to suffer more with this pest than kharif crop.
Nature of damage: The incidence would start from seedling stage and prevail right through entire plant life. Stunted growth of plant, cupped and crinkled leaves, burnt appearance of leaf margins are symptoms of damage.
Life history: The female lays on an average 15 eggs into the spongy parenehymatous tissue between the vascular bundles and the epidermis and they hatch in 4 – 11 days. The nymphs moult five times and the whole life cycle is completed in two weeks to more than a month and a half depending upon the temperature and humidity prevailing in the field.
(i) Insecticides like phosphamidon (0.03%) or dimethoate (0.03%) or monocrotophos (0.05%) or imidacloprid (0.01%) may be sprayed @ 650-700 litre spray solution per hectare if the pest build up is very high.
(ii) Seed treatment with imidacloprid @ 5g and 7.5 g/kg of sunflower seed protects from jassid up to 35 – 40 days after sowing.
2. Capitulum borer, Helicoverpa armigera (Hubner) (Noctuidae : Lepidoptera)
Distribution : The capitulum borer, H. armigera is highly polyphagous with about 181 host plants including important crop plants such as pulses, cotton, vegetables, oilseeds etc. and the pest is prevalent throughout India.
Nature of damage: The larva is capable of developing on foliage which is rather less common in field’s situations. On a bloom, usually, larvae on hatching would get into the bottom of the preripheral florets and feed on ovaries. During pre-anthesis stage they feed scraping the bracts first and later feed through ray-florets which cover disc florets and finally find access to immature ovaries. The larval growth is better supported by developing seeds.
Life history: H. armigera passes through four generations in Punjab and seven to eight generations in Andhra Pradesh. Several crops like maize, sorghum, cotton, sunflower, tomato, pigeonpea, chickpea etc., are found to support large populations of H. armigera.Emergence of H. armigera moth has been observed evening any time after 1600 hrs. the peak emergence being between 20.00 and 22.00 hr.
Pre-oviposition period ranged from 1 – 4 days, oviposition period 2 – 5 days, and post oviposition period 1 – 2 days. Each female moth can lay on an average 700 – 1000 eggs. The incubation period ranges from 2 – 5 days. There are normally six instars, but exceptionally seven instars are found in cold season. The larval period ranges from 8 to 33.6 days with 8 to 12 days on tomato, 21 – 28 days on chickpea, 21 – 28 days on maize, 33.6 days on sunflower and 20 – 21 days on cotton. The full grown larvae pupate in earthen cocoons in the soil. Pupal period vary from 5 – 8 days in India.
(i) A significant reduction in pest density is achieved with the spray of NPV @250 LE*/ha.
(ii) NSKE (5%) and many neem origin pesticides are found effective in reducing damage due to H. armigera.
(iii) Endosulfan (0.05%) on 25 and 45 DAS is ideal for management of this pest in a short duration variety like Morden.
(iv) Endosulfan (0.05%), cypermethrin (0.005%), fenvalerate (0.005%) and deltamethrin (0.002%) spray @ 650 – 700 litre/ha against the head borer are found to be effective.
* LC = Larval Equivalent
3. Tobacco caterpillar (Spodoptera litura) (Fabricius) (Noctuidae: Lepidoptera)
Distribution: It is cosmopolitan, highly polyphagous and is reported on sunflower in all sunflower growing areas.
Nature of damage : Early instar larvae (gregarious phase) scrape on green matter that give a mesh like appearance to damaged leaves which can be spotted easily from a distance. Older larvae cause total defoliation.
Life history: Adult moth has dull brown forewings with white markings, hind wings are hyaline. Eggs are laid underneath the leaves in clusters (200 – 300 eggs) covered with cream coloured hairs and scales. Egg period is 3 – 4 days. Larvae are gregarious when young, later disperse having 5-6 instars. Larval duration ranges from 15 – 28 days. They feed on foliage at night, hide in soil and debris during day. The larvae pupate in the soil in an earthen cell. Pupal period is 7 – 10 days.
(i) Monitoring of moth activity through pheromone traps.
(ii) Collection and destruction of egg masses and gregarious early instars present on undersurface of leaves.
(iii) Spray of monocrotophos 0.05% or dichlorvos 0.05% or cypermethrin 0.005% in 500 litre water/ha in case of severe incidence.
(iv) Use of poisoned bran bait (125 ml monocrotophos + 1 kg jaggery + 10 kg rice bran) is effective against later instars.
4. Bihar hairy caterpillar (Spilosoma oblique) (Walker )(Arctiidae: Lepidoptera)
Distribution: It is highly polyphagous and mainly a pest of rabi-summer sunflower in Maharashtra.
Nature of damage: The larvae are foliage feeders. Early instars feed on chlorophyll and later instars defoliate the crop. Drying up of infested leaves is a characteristic symptom.
Life history: Adult moth lays eggs in clusters. Larvae are hairy, gregarious in early instars and disperse later. Larval period varies from 14 – 21 days. Pupal diapause is noticed. Generation time is 38 – 164 days.
(i) Collection of infested leaves which show characteristic drying symptoms will reduce the population to a great extent because of the gregarious nature of young larvae.
(ii) Spraying contact insecticides endosulfan or quinalphos or carbaryl at 0.05 – 0.1 %.
5. Green semiloopers Trichoplusia ni, Thysanoplusia orichalcea (Fabr.) (Plusia orichalcea) (Noctuidae: Lepidoptera)
Distribution: Regular pest of sunflower in Maharashtra, Karnataka during August and September. It is also found to attack cotton, legumes, solanaceus plants, sweet potato and some cucurbits.
Nature of damage : Early instars feed on chlorophyll of tender leaves causing transparent leaf spots, later feed from leaf margin and defoliate leaving midribs in case of severe incidence.
Life history: Larvae are green in colour with a thin white lateral line and two white lines on the back, active and form loop in motion; swollen at posterior end and tapers anteriorly. Pupate in white transparent silken cocoons in leaf litter or crop debris. Life cycle takes 30 days.
(i) Spray quinalphos 0.05% in case of severe incidence.