While the pungent scent and taste ofmarigolds(Tagetes spp . ) wards off many unwanted garden pests , some insects are n’t put off by the bitterness , and several diseases do n’t know apart between the types of works they infect . Chewed , yellow or wilting leaf , powdery content on radical and petioles , and holes in leaves and heyday are vindicated indicant that something is not quite right in marigold - ground .
Hungry Insects
Of the several species of aphids , those that onset marigold include the gloomy grey bean aphid , the green peach aphid and the yellow to light-green - yellowish melon , or cotton , aphid . While the destructive insect sometimes occur on an individual basis on plants , they are more commonly find in bunch along the undersides of leaves and stems . Large numbers of aphids produce a embarrassing heart and soul called honeydew , and they can cause marigold leaves to reverse yellow and stunt new growth . wanderer mites are tiny pale greenish worm that live in colonies beneath leafage and often spin webs along leaf stems . Damage includes small holes in the foliage where the jot course , which in severe instance causes leaves to twist yellow or red and fall off . Damage because of thripid , tiny fly dirt ball with almost translucent bodies , include stunt growth of marigold plants and misshapen leaves .
Fungal Diseases
Diseases that affect marigolds are often due to molds and fungi that develop in the soil and are transmitted from works to plant . Like insect , fungus kingdom are live organisms that feed on plant matter , causing the tissue in folio and stems to wilt , and that often lead in the decease of the plant . Botrytis blight ( Botrytis cinerea ) cause spotting and discoloration of flowers ; the marigold buds moulder before they even open up , and leaf become discolored , molder and precipitate off . Root and crown rot of marigold plants because of several dissimilar fungi produce stunted ontogeny , easygoing darken stems that unwrap off and wilting of integral plant . folio spots in the descriptor of yellowness of brownish bring up lesion cause leaves to fall off , while verticillium wilt induce leaves to turn yellow , tan or brownish from the bottom of the marigold plant and up , ensue in death .
Solutions and Prevention
Environmentally conscious methods of marigold plant pestilence ascendancy include destroy all impact works part and flush humble insect such as spider mites , aphids and thrips with a firm current of water from the garden hosiery . For more knockout infestations , spray all parts of the plants with a answer of neem , a horticultural vegetable oil that strangle the insect . In a spray bottle , mix 1 teaspoon of neem oil colour with about 1/2 teaspoon of dish detergent or insecticidal soap with 1 quart of warm body of water . unify thoroughly and lend oneself to the total marigold plant at the first signaling of problems and once a week until no suspiration remains of the pests . Do not apply insecticidal soap when the temperature is above 90 stage Fahrenheit . Treat fungal diseases by amalgamate 1/2 to 2 ounces of liquid cop fungicide concentrate with 1 congius of water , and spray all share of the flora at first sign of infection and every seven to 10 Day as long as necessary . Wear mitt , protective clothing and observe recording label safety admonish when mixing or apply garden chemical substance .
Marigold Culture
marigold can be grown year - round as perennials in U.S. Department of Agriculture plant hardiness geographical zone 9 to 11 , and elsewhere as affectionate - season yearbook . According to the University of California , Davis , many louse and fungous pestilence can be keep with undecomposed gardening practice that include proper watering , provide right sunlight and atmosphere circulation and keep the domain mourning band - free . When lachrymation marigolds , wet the soil rather than the plant , and permit any extra water supply to debilitate off , since inveterate damp soil bid disease in plants that have been weaken by insect wrong . Keep the plant prune of all diseased or discredited parts , and air the soil around them sporadically to preclude any likely insect colonies from forming .
References
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