Marigold.pptx

Diseases of marigold

1. PESTS OF MARIGOLD

2. Marigold The African Marigold  ( Tagetes erecta ) French Marigold  ( Tagetes patula ) In genus Tagetes there are 33 species, but commercially two species T. erecta and T. patula are grown in our country and in western countries another species T. tenuifolia is also grown.

3. 1. Bud caterpillars Helicoverpa armigera and Phycita sp . Activity: Marigold is one of the preferred host of H.armigera Nature of damage H.armigera Eggs are laid singly on young buds. Hatched larvae bore into buds and growing flowers and feed on developing flowers by damaging florets and petals On an average 4-5 larvae are seen per plant Phycita sp. Larvae of Phycita sp. damage flowers by making groove on the central receptacle and feed on ovaries and stamen filament Excreta on damaged flowers

4. Management Collection and destruction of infested buds and flowers and matured larvae reduce further damage. spray HaNPV @250LE/ha Setting up of light traps to attract and kill the adults. Spray of NSKE @ 4.0 % Emergency spray of spinosad @ 0.4ml/L or indoxacarb @ 0.6 to 0.7ml/L or flubendiamide @ 0.2 to 0.5ml/L or coragen @ 0.3ml/L

5. 2. Aphids, Aphis gossypii   ( Hemiptera:Aphididae ) Nature of damage Aphids mainly infest lower surface of flowers and base of petals. Nymphs and adults suck the sap from the flowers causing discolouration and withering. Infected plants become weak and unproductive.  Aphids can cause a lot of damage to marigolds, including stunted growth, mottled leaves, lowered rates of growth and curled foliage. With infestation by aphids, marigolds will have sticky secretions over their newer buds and leaves.

6. Identification These are small insects green to bluish-grey or black in colour. These usually occur in clusters and damage the apical growing portion by sucking the plant sap. Management The pest can be controlled by need based spraying of crop with pymetrozine 50 WG @ 0.6g/L or flonicamid 50 WG @ 0.3g/L.

7. 3. Red spider mite,  Tetranychus urticae ( Acarina : Tetranychidae ) Activity: The mites become active during the flowering period , August-September, November Nature of damage: These are spinning creatures, red and brown in colour Colonies of mites are found on lower surface of leaves which are covered by dirty webs Both nymphal and adult stage feed on plant sap Affected leaves discoloured The speckling, discoloration and dusty appearance of the leaves easily identify the attack Attacked plants get stunted in growth, wilt and dry if damage is severe

8. Management Cut and burn the severely infested plant parts Thoroughly spray water on plant for dislodging the webs Spray miticide like dicofol @ 3 – 5ml/L or spiromesifen @ 0.6 to 0.8ml/L or propargite @ 1ml/L followed by a spray of pongamia oil @1% is recommended for effective control.

9. 4. Leaf miner, Liriomyza  spp. ( Diptera : Agromyziidae ) The most important species are Liriomyza trifolii and the pea leafminer ( L. langei ). Identification Adult  Liriomyza  are small, active, black and yellow flies. Larvae are yellow cylindrical maggots that feed beneath the leaf surface.

10. Nature of damage: Adult female leaf miners puncture leaves and sometimes petals to feed on exuding sap. These punctures eventually turn white, giving foliage a stippled or speckled appearance. The most obvious evidence of leaf miners is the twisting trails (or mines) the larvae leave as they feed beneath the leaf surface. The mine becomes longer and wider as the larva grows. Mining usually has little impact on plant growth and rarely kills plants. Unusually heavy damage can slow plant growth and may cause infested leaves to drop. Management: Remove and destroy severely mined leaves to reduce further damage Spray NSKE 5% or chlorpyriphos @ 2ml/L or abamectin or Fipronil @ 1.5ml/L.

11. 5. Thrips , Thrips tabaci ( Thysanoptera : Thripidae ) Damage symptom Thrips prefer to feed in rapidly growing tissue. Discoloured or distorted plant tissue is the clues that thrips are present. Damaged leaves become papery and distorted. Infested terminals may discolour, rolled and drop leaves prematurely.  Petals may exhibit “colour break,” which is pale tissue that was killed by thrips feeding before buds opened. Control   measures Set up blue sticky trap 20 per acre The pest can be controlled by need based spraying of crop with pymetrozine 50 WG @ 0.6g/L or flonicamid 50 WG @ 0.3g/L.

12. 6. Mealy bug: Planococcus citri   ( Hemiptera : Pseudococcidae ) Damage symptom : Mealy bugs are crowdly present in young shoots, stem and leaves. Flattening and crinkled with dark green leaves. It secrets honey like substances because of that leaves are converted into black sooty mould. Apical parts of the shoots show retarded growth.

13. 7. Leaf Hoppers, Amrasca biguttula biguttula ( Hemiptera : Cicadellidae ) Activity: cause considerable damage to the foliage of the plant, particularly during rainy season.  Symptom of damage The symptom appears as rolling and curling of leaves along with wilting of shoots. French marigold is more susceptible than African type. Infested marigold leaves become cupped; their edges roll in toward the midrib and twist on their stalks. Branch tips and leaflets may wilt, which inhibits blooming. Leaves yellow and dry out, those that are exposed to bright sunlight turning purplish first. Some common signs of infestation by leafhoppers are the leaves becoming disfigured and discoloured in appearance. Some leafhoppers spread virus diseases such as aster yellows .

14. Identification: Leafhoppers are strikingly colored, blunt-profiled bugs, 1/4 to 1/3 inches long, wedge-shaped, with wings held in a rooflike position above their bodies. They're very active, moving sideways or hopping suddenly when disturbed.

15. Management Rogue out infested plants as soon as they appear in the field and completely destroy them. The pest can be controlled by need based spraying of crop with pymetrozine 50 WG @ 0.6g/L or flonicamid 50 WG @ 0.3g/L.

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