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Ways of controlling weed on trees

Lichen growth is most prevalent on the adaxial (upper) surface of leaves such as coffee, citrus and avocado, which possess a natural thick waxy cuticle. (Image source: Terry Mabbet)

Epiphytes 1Copper fungicide also controls epiphytic plant growth

Heavy epiphytic growth on tropical tree crops requires control but economics of production and especially cocoa means that application of chemicals dedicated to the control of epiphytes are not economically worthwhile, especially for smallholders.

Copper fungicides, the most widely and intensively deployed protectant fungicides and used to routinely control fungal and fungus-like (Phytophthora) diseases are also active against these epiphytes on trees. The divalent copper ion (Cu2+), the active principle of fixed copper fungicides including cuprous oxide, cupric hydroxide and copper oxychloride, has an exceptionally broad spectrum of activity covering lichen, algae, mosses, liverworts, ferns and other epiphytes.

Of all the fixed copper fungicides, cuprous oxide contains the highest proportion of active copper in the molecule and is therefore the most active on a gram for gram basis. Cuprous oxide is routinely sprayed on cocoa to control Phytophthora pod rot and stem canker, to coffee for control leaf rust (Hemileia vastatrix) and coffee berry disease (Colletotrichum coffeanum), on citrus to control anthracnose (Colletotrichum spp), greasy spot (Mycosphaerella citri), sour orange scab (Elsinoe fawcetti) and melanose (Diaporthe citri), and for anthracnose (Colletotrichum gloeosporioides) of mango and avocado. Routine sprays of cuprous oxide to control these diseases on their respective host tree crop will additionally keep trees (leaves and bark) free from epiphytic growth.


Dr Terry Mabbett