Saturday , 17 June 2017

Marigold in Bio-control

Miguel Braganza
It is Goa’s alternative for the ‘Rose’ flower which we call ‘Gulab’ and know the Marigold as ‘Rosam’. The confusion does not end there: Tagetes erecta, as it is known by Botanists, originated in South America but is known as ‘African Marigold’! It is a little different from Tagetes patula, the ‘French Marigold’ that actually gave the flower its name, a corruption of the term ‘Mary’s gold’, because these flowers with golden petals were offered in plenty at the shrines of Mary across the tomato growing belt of Mediterranean Europe. The nativity of Mary is celebrated on September 8 and it coincides with the peak flowering of marigolds. So does Dusshera or Vijaya Dashmi, when the whole of India worships the tools of the trade even if now there is no longer the need to sharpen the swords to go to war as the Marathas under Shivaji did. The current wars are fought from corporate board rooms and the price of World War-III to control food production worldwide is currently pegged at 66 billion dollars for a deal between the two major players of the WW-II, Monsanto of USA and Bayers of IG Farben (IG or ‘Interessengemeinschaft’ stands for ‘Association of Common Interests’. IG Farben included BASF, Bayer, Hoechst, and other chemical and pharmaceutical companies of war time Germany). This time Germany seems to be winning.
Incidentally, the marigold can be a symbol for the war against cancer-causing agro-chemicals, which are actually disguised war chemicals based on phosphorus and manufactured by the same set of companies. The root exudates of marigold plants are most effective against the root-knot nematode Meloidogyne incognita and the root lesion nematode Pratylenchus penetrans . The farmers will often treat their soil with various pesticides, called nematicides, in an attempt to eliminate the damage caused by an infestation. In doing this, farmers will also kill many of the beneficial soil fauna like earthworms, which leads to degradation of soil quality. The fungal biocontrol agent, Paecilomyces lilacinus (PL251), was able to reduce root knot on tomato by only 66 per cent. Growing marigolds has been shown to reduce nematode numbers by 90 per cent in the field and produce flowers that have other uses. The flowers are used in garlands, in aroma therapy, to produce apple flavor and yellow colour for food and drinks, and fed to hens to get deep orange egg yolks.
Root-knot nematode affected tomato, cucumber, brinjal (eggplant), bhendi (okra or Lady’s Finger), pumpkin (squash), and other susceptible crops will have very conspicuous root galls or knotty swellings on the roots. Lesion nematode, on the other hand, causes the roots to disintegrate in patches which may later join together. Root lesion nematode has a wide host range, including hosts like roses, banana, tomato, potato, maize, onion, field bean, cowpea, and chickpea. The nematode lays two eggs per day and completes its life cycle in just 22 days at 30 degrees Celsius temperature. The life cycle doubles at 17 degrees Celsius and egg-laying is almost half. Marigold can put a full stop to nematodes in the field, naturally.

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