Rottboellia cochinchinensis

Rottboellia cochinchinensis itchgrass, pricklegrass, guinea fowl grass

Here is a real nasty emerging weed which I have noticed popping up all along the KwaZulu-Natal north coast. Watch out for it eradicate as soon as it is discovered before it gets out of hand.

A quick search on the internet turned up the following information about Rottboellia cochinchinensis

Rottboellia cochinchinensis

Distribution

A native of Indo-China, which has naturalised throughout the tropics of Asia, in north-eastern Australia and the savannah zones of Africa including South Africa.

Rottboellia cochinchinensis has been introduced throughout the Caribbean, Tropical America and the southeastern and central United States. Although it may occur under a variety of moisture, light and soil conditions, at a wide range of altitudes, Rottboellia cochinchinensis is most commonly found on sunny, disturbed sites with high rainfall or irrigation in subtropical and tropical climates.

Distinguishing Characteristics

Rottboellia cochinchinensis is an erect, annual grass that can grow to 3m high. Stilt roots often develop at the base of the stem. Plants produce abundant side shoots and grow into large clumps. The leaf sheath and the lower portion of the leaf blade are usually covered with stiff hairs that have a small swelling (tubercle) at the base. 

These hairs break off on contact, penetrating and irritating the skin. The leaf blades, which measure 150mm to 500mm inches long and up to 25mm wide, typically have broad white midribs and scabrous (rough to the touch) margins.

The ligule is a membranous, ciliate flap, to 3mm long. The slender, cylindrical, unbranched inflorescence is segmented. Each heteromorphic segment consists of two types of spikelets:  a sessile (stalkless), fertile spikelet that is embedded in the axis of the inflorescence and a pedicellate (stalked), often sterile spikelet with the pedicel fused to the internode of the inflorescence axis. The spikelets are awnless, narrowly ovate to triangular in shape, and somewhat flattened. 

At maturity, the seedhead breaks into segments, with the paired spikelets attached. A small, cylindrical gland-like projection, known as an elaiosome, is located at the base of each segment. Rich in lipids and proteins, the elaiosome attracts ants that help to disperse the seed.

Environmental  and Economic impact

Rottboellia cochinchinensis is an invasive aggressive weed under various ecological conditions, in at least 18 crops in 44 countries. It is estimated that more than 3.5 million ha of cropping lands are infested with Rottboellia cochinchinensis in Central America and the Caribbean

Rottboellia cochinchinensisis a serious weed of cotton in Zambia and Zimbabwe and a moderate weed of cotton in Ethiopia, Mozambique, Sudan, Uganda and Venezuela; a serious weed which effects on crop yield,

It competes for soil nutrients, water and light, resulting in reduced crop yields, and also hosts insect pests and diseases that affect graminaceous crops.

Under optimal conditions, Rottboellia cochinchinensis plants may begin producing seed six to seven weeks from emergence and continue to produce seed throughout the growing season. A single plant can yield between 2,000 and 16,000 seeds.

Recent research (Meksawat and Pornprom 2010) has shown that Rottboellia cochinchinensis is allelopathic releasing contains chemicals that inhibit the germination and growth of nearby plants.

The irritating hairs on the leaf sheaths discourage foraging by livestock and wild herbivores.

Rottboellia cochinchinensisis a problem to labourers, as the needle-like hairs on the leaf sheaths break off in the skin and can cause painful infections.

Michael Hickman

Landscape Design and Rehabilitation Specialist

www.ecoman.co.za

michael@ecoman.co.za

20.03.16

Please do not leave this page without clicking on the G+ button below if you do not have a Google profile it is about time that you registered for one 

Vasey Grass Paspalum urvillei

Vasey grass Paspalum urvillei is a highly invasive grass which is a native of Argentina and Uruguay which is mostly found growing in damp and disturbed localities in our area.

 A monospecific stand of Paspalum urvillei

Paspalum urvillei is a large dominant grass which produces vast amounts of viable seed that displaces other grasses to form large monospecific stands largely by means of allelopathy and direct competition for resources such as sunlight, water and nutrients.

This photo gives one an idea of the average size of Paspalum urvillei

Allelopathy refers to the beneficial or harmful effects of one plant on another plant, due to the release of biochemicals, known as allelochemicals, from plant parts by leaching, root exudation, volatilization, residue decomposition, and other processes.

This photo give a clearly shows that Paspalum urvillei 

completely displaces all other species

What alarms me most about this invasive alien grass and why I see it as a huge threat in areas that are being rehabilitated is that it spreads very rapidly and colonizing vast areas and that there are no selective herbicides available that can be used to selectively eradicate it as in the case of broad leafed and other non-grassy weeds. The only options to remove this invasive grass are to dig it out or the use of non-selective herbicides such as Glyphosate which would destroy all other vegetation in the areas being dealt with therefore the sooner stands of this invasive grass are located and are eradicated the better before their seed bank increases and spreads.

Michael Hickman

Landscape Design and Rehabilitation Specialist

www.ecoman.co.za

michael@ecoman.co.za

16.03.16

Please do not leave this page without clicking on the G+ button below if you do not have a Google profile it is about time that you registered for one 

The important role of the humble Dung Beetle in natural ecosystems

Dung beetles play a very important role in the health ant the fertility of natural grassland

Ancient Egyptians thought very highly of the dung beetle, believing that the dung beetle kept the Earth revolving like a giant ball of dung, linking the insect to Khepri, the Egyptian god of the rising sun.

Dung beetles belong to the family Scarabaeoidea; with most of the species being placed in the subfamilies Scarabaeinae and Aphodiinae (scarab beetles). Most species of Scarabaeinae feed exclusively on feces and are known as true dung beetles. There are dung-feeding beetles which belong to other families, such as the Geotrupidae (the earth-boring dung beetle). The subfamily Scarabaeinae alone has more than 5,000 species.

The dung beetles known as rollers, roll dung into round balls, which are used as a food source for their larvae to develop on are rolled and buried in brooding chambers that are dug into the ground. Others, known as tunnelers, bury the dung wherever they find it. A third group, the dwellers, neither roll nor burrow, they simply live in manure.

Spider Dung Beetle Sisyphus specie with dung ball

Dung beetles live in many habitats, including desert, farmland, forest, and grasslands. They do not prefer extremely cold or dry weather. They are found on all continents except Antarctica. They eat the dung of herbivores and omnivores, and prefer that produced by the former. Many of them also feed on mushrooms and decaying leaves and fruits. Those that eat dung do not need to eat or drink anything else, because the dung provides all the necessary nutrients. Most dung beetles search for dung using their sensitive sense of smell. Some smaller species simply attach themselves to the dung-providers to wait for the dung. After capturing the dung, a dung beetle rolls it, following a straight line despite all obstacles. Sometimes, dung beetles try to steal the dung ball from another beetle, so the dung beetles have to move rapidly away from a dung pile once they have rolled their ball to prevent it from being stolen. Dung beetles can roll up to 10 times their weight.

Male Onthophagus taurus beetles can pull 1,141 times their own body weight: the equivalent of an average person pulling six double-decker buses full of people. No wonder the dung beetle is known as one of the strongest animals for its size.

Spider Dung Beetle Sisyphus specie showing very long  hind legs

In 2003, researchers found one species of dung beetle the African Scarabaeus zambesianus navigates by using polarization patterns in moonlight. The discovery is the first proof any animal can use polarized moonlight for orientation. In 2013, a study was published revealing that dung beetles can navigate when only the Milky Way or clusters of bright stars are visible the only insect known to orient itself by the galaxy.

The "rollers" roll and bury a dung ball either for food storage or for making a brooding ball. In the latter case, two beetles, one male and one female, stay around the dung ball during the rolling process. Usually it is the male that rolls the ball, while the female hitch-hikes or simply follows behind. In some cases, the male and the female roll together. When a spot with soft soil is found, they stop and bury the ball, then mate underground. After the mating, both or one of them prepares the brooding ball. When the ball is finished, the female lays eggs inside it. Some species do not leave after this stage, but remain to safeguard their offspring. The larvae live in brood balls made with dung prepared by their parents. During the larval stage, the beetle feeds on the dung surrounding it. The dung beetle goes through a complete metamorphosis.

Dung beetles play a highly important role in the environment by taking animal dung that could spread various diseases amongst grazing animals and burry it in the root zone where it can be useful to the veld grasses, herbs, bacteria and fungi not leaving out the fertility and general health and structure of the soil. By burying and consuming dung, dung beetles improve nutrient recycling and soil structure simultaneously protecting domestic livestock, such as cattle goats and sheep as well as indigenous game from disease by removing the dung which, if left, could provide habitat for pests and diseases.

Most dung beetles specialize on the dung of particular animals, or types of animals, and will not touch the dung of other species.

 

Spider Dung Beetle Sisyphus specie sitting on top of dung ball

Sisyphus species - spider dung beetles

Small to medium beetles 3-12 mm black dark grey or brown hind legs very long move very energetically

Adults congregate to feed on fresh dung in particular the dung of small animals. They also feed on the dung of tortoises, birds, toads and large carnivores. The Sisyphus species form dung balls which they roll away to be buried approximately 50 mm below the surface. A single egg is laid in each ball. Sisyphus species are particularly active on hot humid days following rain. Like magic dung that has been dropped on the ground disappears due to the efforts of these highly energetic little creatures. In my case they are particularly attracted to the dung of my sheep in preference to goat dung.

Video

Spider Dung Beetles Sisyphus specie rolling a dung ball 

Michael Hickman

Landscape Design and Rehabilitation Specialist

www.ecoman.co.za

michael@ecoman.co.za

25.01.16

Please do not leave this page without clicking on the G+ button below if you do not have a Google profile it is about time that you registered for one 

Yellow Justicia

Justicia flava

Justicia flava is known as impela in Zulu

Justicia flava

Justicia flava is an erect or trailing, usually perennial herb growing up to 120cm tall which belongs to the family, Acanthaceae. The stem often becomes woody at the base

Justicia flava is a common species found in a number of different habitats especially in disturbed habitats, growing on a wide range of soil types, in full sun or semi-shady areas at elevations from sea-level to 2,300 metres, some forms of the plant can tolerate moderate frost. It has a widespread distribution from West Africa through Central extending into Southern Africa, also occurs on the Arabian Peninsula. Justicia flava is extremely drought resistant, in very dry regions the plant can grow as an annual with smaller flowers.

Justicia flava is pollinated by insects in particular honey bees it also attracts various species of butterflies in particular small blues of the family Lycaenidae.

Cultural uses

The plant is harvested from the wild for local use as a food and medicine. In some areas Justicia flava is not removed when found growing as a weed in cultivated fields, but is allowed to grow on in order to harvest its leaves for use as a vegetable which is cooked as a spinach of used in soups and stews. In some regions the leaves are burnt to ash to produce a vegetable salt. Although it is reported that Justicia flava makes good forage for domestic animals I have observed that it is not eaten by my sheep and goats.

Justicia is used traditionally to treat coughs in South Africa. The roots are traditionally rolled into beads which remain fragrant for years.

Growing Justicia flava

Justicia flava is best grown from seed although it grows easily from cuttings

The seed capsules of Justicia flava burst open when ripe, to prevent the seeds from being lost, they must be collected as soon as the seed capsules turn brown. The seeds can be planted into trays or pots but by far the easiest is to plant the seed which germinates readily directly in situ.

Justicia flava grows best in a sunny position, but also tolerates partial shade.

Environmental value and use in the garden

Bees visiting Justicia flava

Justicia flava makes a wonderful ornamental groundcover for use in sunny spots where it can be used as a ground cover to protect and bind the soil for instance in coastal dunes and sandy river banks. It is a very valuable source of both nectar and pollen for honey bees in particular because it flowers year round under favourable conditions. In my own garden Justicia flava attracts very large numbers of insects year round at times of the year being the main source of food for them.

Warning

Justicia flava reproduces readily from seed which is most useful if it is being used for the stabilization of sandy soil but it can become a “weed” in the more formal garden. In my own garden I periodically remove the old plants to keep them under control.

Michael Hickman

Landscape Design and Rehabilitation Specialist

www.ecoman.co.za

michael@ecoman.co.za

19.01.16

Please do not leave this page without clicking on the G+ button below if you do not have a Google profile it is about time that you registered for one 

Berkheya insignis

Introducing a magnificent grassland herb from South East Africa that is practically unknown to the nursery and horticultural industry that deserves a place in every garden with a suitable climate.


Berkheya insignis is a perennial grassland herb found growing mostly on rocky slopes which grows to 400-600 mm in height belonging to the family Asteraceae, the Sunflower family.

The flowers which are a bright yellow are large 80 mm and up to over 100mm in cultivation

Berkheya insignis flower

Berkheya insignis is hardy, drought resistant and easy to grow, growing well in heavy clay soils provided they are well drained.

Berkheya insignis can be propagated from division, cuttings and seed

Berkheya insignis flower with beetle

Berkheya insignis attracts insects especially small colourful beetles

Michael Hickman

Landscape Design and Rehabilitation Specialist

www.ecoman.co.za

michael@ecoman.co.za

16.01.16

Please do not leave this page without clicking on the G+ button below if you do not have a Google profile it is about time that you registered for one