Gauteng Smallholder Gauteng Smallholder November 2011 - Page 35

IN THE ORCHARD The meaning of lichen on your trees T rees are so important on smallholdings, for a number of reasons, so when we see lichen growing on any of them, particularly our fruit trees, we might become concerned. Lichen ~ pronounced “liken” ~ is a grey, green or yellow patch that we sometimes see on trees, rocks, shrubs or even on buildings. It is actually a complex From page 31 ment must also include how you manage the grazing. In order to decrease the parasite load in the pasture, you should reduce the length of stay in a pasture, by rotating amongst camps. Chances are you!ve seen lichen on your trees, but do you know what it is and what it does? organism, consisting of fungi and algae or bacteria growing together in symbiosis. Symbiosis means that two organisms are growing together, usually in a relation- ship that benefits both. The fungus needs a partner that can carry out photosyn- thesis. Fungi are incapable of photosynthesis because they lack the green pigment chlorophyll. Fungi cannot harvest light energy from the sun and generate their own nourishment in the form of carbohydrates. Instead, they need to seek out outside Ticks do not survive for long on pasture that is either heavily grazed and thus short and dry, or in areas where pasture land is rotated with crops. When intensively farmed land is fenced it is possible for cattle pastures to be cleared of ticks by a combination of management and acaricide use, and then maintained tick free. Burning of pasture grasses kills many ticks but should only be used when the main reason is to improve grazing availability. You might also need to spray the pens where the livestock are kept at night. TICKS 33 sources of food.The algae or bacteria live inside the fungus, and exchange nutrients with it. Cyanobacteria also provide fungi with the additional benefit of nitrogen fixation. In return, fungi provide the algae and cyanobacteria with a protected environment, especially from damaging ultraviolet rays. Lichens are key players in a variety of environmental processes. The lichen sometimes contributes to Continued on page 35