Natural forests and woodlands across Africa can no longer keep pace with the required demand and the resulting deforestation is degrading the environment.
Agriculture too is expanding into natural woodlands and forests therefore the need for farmers to take up growing various tree species eucalyptus being a major one both for forest cover, energy usage, timber and construction work.
In a 2011 paper published by Kilmo Trust about growing of hybrid eucalyptus species in East Africa, it is stated that wood is an embedded and vital part of the lives of most people in East Africa.
Poor rural and urban communities in particular rely on wood for energy and for construction.
The statistics indicates that in 2007 the demand for wood in Kenya, Tanzania and Uganda was more than 94 million cubic metres mainly for cooking.
Against this background, science experts specialised in tree breeding note that it is important for farmers in East Africa including Uganda to take up growing of eucalyptus trees because of its economic viability.
Best eucalyptus species
The former Director National Forest Resources Research Institute (NaFORRI) Dr Francis Osoto Esegu explaining best agronomy practices farmers growing eucalyptus can adopt notes that there are over 100 species in existence in the country but only five to eight species are well adopted by farmers.
The major specie being eucalyptus grandis and saligna species which is suited to cooler and wetter areas around Lake Victoria belt and eucalyptus camaldulensis which grows well in hotter and drier climates.
He explains that eucalyptus grandis grows across the country as long as the area is moderately wet including the highlands in Western Uganda and the West Nile region.
Giving the history he says eucalyptus was introduced in Uganda in 1898 from Australia in the botanical area in Entebbe. This was to control sucking of swampy water that harbors mosquitos in the country. The species were eventually taken to Mbale in Eastern Uganda, Masaka and farmers throughout the country adopted it mainly as a source of energy and for construction.
Farmers are now growing clonal hybrid eucalyptus salicola species across the country.
Drier areas such as the Karamoja region, eucalyptus ellipsoidea species suits best because it is drought prone.
Dr Osoto explains that NaFORRI tested about 12 hybrid eucalyptus species across the country and eucalyptus grandis and eucalyptus saligna were planted in southern Uganda and eucalyptus camaldulensis and eucalyptus tereticornis were planted in the relatively drier eastern and northern regions which most farmers in the respective regions have adopted.
He explained that it is important for farmers to know that they can plant eucalyptus seedlings bred in a nursery as well as cloned hybrid varieties.
Most traditional species can be grown directly from eucalyptus seed planted in a nursery bed.
It is important to use light potting mix with sand. The seed should have been kept moist before planting in the pot. It should be sown on top of the soil surface and covered with a fine soil layer.
The seedlings should be placed in bright light immediately after germination for proper sprouting. Light necessary for root development.
Once it grows forming two to three leafs then it is ready for transplanting in the field.
This should be done when the rains start probably in the month of March and April.
However most farmers are now growing cloned hybrid species where the seedlings are raised in a nursery bed through cuttings.
It is important to select a young tree stem from a preferred species because older stems may not produce roots.
The cuttings should be three to five inches long and have four to eight leaves. Use pruning shears to make a clean cut just below a leaf node.
Set the cuttings in a bucket of water.
Pests and diseases
According to Dr Osoto the commonest pest destroying eucalyptus tree in farmer fields’ from tender stage is philid, a tiny insect which sucks up water from the leaves causing drying.
Other soil bone diseases include powdery mildew which is a fungal disease that forms a whitish coating and causes young leaves to curl.
Mycosphaerella leaf spots found on older leaves of most eucalyptus hybrid clones and local species, phytophthora root rot which affects mother trees used for producing cuttings.
It rots the roots and after wilting, the leaves, stems, and roots all die.
Cylindrocladium is a disease that prevails in humid climates and it attacks cuttings of clones during rooting causing scourges on young seedlings.
The solution is for farmers to control by spraying the clones with Ridomil (Benlate) and Milraz chemical sprays.
Dr Osoto explains that farmers may sell hybrid trees that have grown for two to three years measuring 6cm for pole usage. In a year, cloned varieties grow about three meters depending on the agronomy practice. For a permanent construction the growth period should be five to six years and for timber about 12 years and above. Traditional trees bred through seed require 6 – 8 years for pole usage and over 12 years for good timer processing.
To Dr Osoto growing of Eucalyptus is a viable income generating initiative for farmers to take up. It serves as woodland forest for climate change adaptation and business related activities when processed. Farmers are advised to grow them in 5 – 10 acre land or beyond in order to reap big.
Dr Osoto notes that it is a myth that most people think eucalyptus trees drain water thereby causing soil degradation. To him there are crops such as tea and sugarcane which drain a lot of water and soil nutrient to grow. As long as a farmer practices the right agronomy, eucalyptus trees according to him are just like any other crop that requires the necessary nutrients to grow.
About the Author
Sylvans Ochola is based at the Department of Crops, Horticulture and Soils, Egerton University.