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Common Name Mesquite Botanical Name Prosopis spp. Status Mesquite is one of only fourteen weeds proclaimed as State Prohibited Weeds in Victoria. This is the highest category to which a noxious weed can be allocated and means that mesquite is to be eradicated if possible from the State. Origin Mesquite is native to northern South America, Central America and southern United States. It was introduced to Australia for stock shelter, food and erosion control. It has limited occurrence in Victoria. Description There are six species or subspecies and hybrids of mesquite recognised in Australia. They vary in height from 1 to 15 m. See the references provided below for more detailed descriptions. Mesquite spp. are usually deciduous and may be small trees or shrubs.  Figure 1: Mesquite plant. Stems - thick, woody; bark may be grey, brown, or very dark to black, and has shallow cracks in it. Older bark is rough. Small branches have smooth bark. A pair of spines is usually present on the main stem or branch above each leaf stalk. Leaves - bipinnate and bright green, consisting of one to three pairs of opposite segments, each segment with 6 to 18 pairs of leaflets. Leaflets are linear to oblong and may be 5 to 12 mm long and 1.5 to 2.5 mm wide. Flowers - greenish yellow, in cylindrical spikes (“lambs tails”) 5 to 10 cm long,. the spikes in clusters of 2 to 5 near the ends of branches.  Figure 2: Mesquite flowers. Seeds - hard, glossy, brown or red brown, ovate to ellipitical; contained in pods 10 to 20 cm long and about 1 cm wide. Mature pods are thick and straw-coloured or purplish, they do not split open like Acacia pods. Each pod contains from 5 to 20 seeds.  Figure 3: Mesquite pods. Roots - extensive and deep. A branched taproot may go down to about 20 m and there is usually a mass of lateral roots near the surface. Life Cycle Seeds germinate after summer rains and most initial growth involves development of the root system. Fire aids in stimulating seed germination. Damage to the topgrowth or surface roots may stimulate vegetative shoots from otherwise dormant buds at the base of the main trunk some 15 to 20 cm below the soil surface. Growth from these buds creates multi stemmed plants. Branches which hang sufficiently to become covered with soil will also take root and produce a new plant. Mesquite does not flower until 2 to 3 years old. Flowering occurs in summer and seeds are mature within about 1.5 months. Dispersal Mesquite has been distributed by introduction as shade, shelter or fodder plants for livestock and by the stock eating and passing the seed. Vegetative reproduction is responsible for increasing the density of infestations. General Mesquite can grow in seemingly harsh conditions and be a source of stock food in such situations. However, mesquites are aggressive competitors. They can invade grazing land causing loss of grass cover and create stock access problems to waterholes. Distribution of mesquites in Victoria is limited to near Swan Hill, Wycheproof and Wangaratta. Chemical Control No products are registered in Victoria to control this weed. Important Any person who believes they have located an infestation of mesquite, regardless of the area, please notify a Catchment Management Officer at a local office of the Department of Natural Resources and Environment. References
Acknowledgements Prepared by R Williamson, Information & Assessment, KTRI 1996. Updated by I. Faithfull, KTRI, January 1998. This note replaces note number PPA0007 The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication. |
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© The State of Victoria, 1996 - 2008.
This document was published on 26/10/2008.