Lolium: The Grass Genus
Lolium, a type of grass belonging to the bluegrass subfamily in the grass family, is commonly known as ryegrass. However, it’s important to note that the term “ryegrass” may also refer to grasses from other genera.
Characteristics and Distribution
Lolium grasses are known for their bunch-like growth patterns. They originate from Europe, Asia, and northern Africa, but they have been cultivated and naturalized in various regions such as Australia, the Americas, and several oceanic islands.
The plant itself is a short, tufted grass without any hair, and it forms clumps or bunches as it grows. The leaves are smooth and glossy on the lower surface, with parallel veins and untapered edges on the upper surface.
When the leaves are in the bud stage, they are folded lengthwise, giving them a flattened appearance. Unlike Italian ryegrass, Lolium multiflorum, the leaves do not roll up but instead have a strong central keel. The ligule, a small protrusion at the leaf base, is often difficult to see, and the stem is gripped by small white auricles. The leaf sheaths at the base are usually pinkish and hairless. The stems can reach heights of up to 90 cm, and the plant possesses auricles.
Flowering and Inflorescence
The inflorescence of Lolium grass is unbranched, with spikelets positioned alternately along the stem. Each spikelet has a single glume on the side facing away from the stem and contains between 4 and 14 florets without awns (bristle-like projections). The anthers, responsible for pollen production, are pale yellow, and the plant flowers from May to November. Perennial ryegrass has a fibrous root system, with thick main roots and thinner lateral branches. These roots often form mutually beneficial relationships with arbuscular mycorrhizal fungi.
Physiology and Growth Characteristics
Understanding the growth and development of Lolium grasses is crucial for effectively managing them in agricultural settings. Several physiological and morphological features significantly influence the growth, development, and productivity of these grasses.
Lolium grasses, particularly as seedlings, exhibit faster growth rates compared to other cool-season grasses, giving them a competitive advantage in crop or pasture establishment. The formation of leaves and tillers, which are lateral shoots or branches on the main stem, plays a vital role in the overall productivity of Lolium populations. Environmental factors, including sunlight and temperature, directly impact photosynthesis and subsequent growth. Additionally, the availability of nitrogen in the soil significantly influences the growth and development of Lolium grasses.
Negative Impacts and Disadvantages
Ryegrass, when present as a weed, can cause various damages and losses to agricultural crops. Some of the disadvantages of ryegrass as a weed are:
1. Reduction in crop yield: Weeds like ryegrass compete with crops for water, nutrients, and light, leading to significant reductions in crop yield. For example, groundnut yields can be reduced by 40% and chilli yields by 66%. Weeds also contribute to the loss of nitrogen from the soil, amounting to around 150 kg per hectare.
2. Increased cultivation costs: Controlling ryegrass through tillage or chemical methods incurs additional expenses, amounting to approximately 30% of the total expenditure. In heavily infested areas, this cost can further increase, reducing the net profit margin.
3. Decreased quality of field produce: Weed seeds mixed with crop produce during harvesting and threshing can lower the quality of the final yield. As a result, these produce items fetch lower prices in the market, especially leafy vegetables and grain crops.
4. Hosting pests and diseases: Weeds provide shelter and serve as alternate hosts for various insect pests and disease pathogens. This perpetuates the damage caused by pests and diseases. Examples include the gall fly of paddy, midge fly of Jowar, leaf miner of soybean and groundnut, rust of wheat, tikka of groundnut, black rust of wheat, and downy mildew (Saccharum spontaneum).
5. Interference with water flow: Weeds obstruct drainage and disrupt the flow of water in irrigation canals and field channels, resulting in seepage losses and reduced irrigation efficiency.
6. Diminished land value: Lands heavily infested with perennial weeds, such as ryegrass, are valued lower due to the high costs involved in bringing them under cultivation.
Management and Control Methods
Greenlife Solutions for Ryegrass Control
To effectively manage ryegrass as a weed, herbicides can be utilized. Herbicides are chemicals specifically designed to control and eliminate unwanted plants, including weeds. Greenlife Crop Protection offers a range of herbicides for managing annual and perennial grasses, including ryegrass.
1. WEMBE 200 SL: This non-selective post-emergence herbicide is effective against ryegrass, broad-leaved weeds, and other unwanted plants. It is applied during land preparation to clear all weeds. The recommended usage rate is 3.0 liters per hectare (300 ml in 20 liters of water).
2. CATAPULT 480 SL: Another non-selective post-emergence herbicide, CATAPULT 480 SL, is used during land preparation to control both ryegrass and broad-leaved weeds. The recommended usage rate is 2.0 liters per hectare (250 ml in 20 liters of water).
3. DIGESTER SUPER 69 EW: This selective post-emergence herbicide targets grasses, including ryegrass, in wheat, barley, and rice crops. It should be applied when the weeds are actively growing. The recommended usage rate is 0.75-1.0 liters per hectare (75-100 ml in 20 liters of water).
By employing these herbicides, farmers can effectively manage ryegrass and maintain the quality and productivity of their crops.