How to Control Algae in Rice Crops

Slime a constant problem in rice crops!

Algae, or slime is a perpetual problem in rice
crops in Australia and elsewhere. In some years
it is so prevalent in the water that large slabs
of algae cover the surface, smothering the emerging
rice crop.

Algae thrives where there are plenty of nutrients in the water and when plentiful sunlight encourages photosynthesis.

The usual rice crop conditions of shallow water, fertilizer and sunlight create an ideal environment for the growth of algae.

During the wet season, the conditions for algae growth are also

enhanced as the water from rivers, creeks and reservoirs used

on the rice crops, contain a higher level of background nutrients.

Algae is commonly present in irrigation water and generally the

rate they multiply is balanced by natural degeneration. However,

when the balance is upset through increased sunshine or by the

introduction of extra nutrients, the rate of growth increases and

the algae blooms become a problem in rice crops.

What are the effects of algae?|seedling germination|seedling knockdown

The obvious signs of algal bloom - great slabs of algae - are like

the tip of an iceberg. Before algae are visually detected a lot of

damage has already occurred to the crop at its most vunerable stage

of growth.

These effects include:

Inhibition of seedling germination and vigour - Plant
pathologists suggest the possible effect of algae could
be greater than that of fungi on germination during early
growth of rice seedlings.

Uprooted seedlings - Respiratory and photosynthetic gases
become trapped in the filaments tangled around seedlings,
uprooting many seedlings which are not yet securely anchored.

Competition for nutrients - Slime lives and grows on the same nutrients as rice seedlings. In a blooming population the sheer numbers of algal cells are enormous and represent a severe drain on the available nutrients.

Seedling knockdown and smother - When filaments of algae are in huge numbers they smother and drown the emerged seedlings and a tremendous amount of damage has already been done. Remedial treatments will salvage the crop but it is obviously better to avoid this damage before it happens. A good seedling stand is essential for high yields.

Present - day treatment

In most cases action to eradicate slime is only taken when filaments

are present in huge numbers. And the treatments available are

limited. Generally farmers use water control or bluestone, both of

which are drastic answers to a problem where a lot of damage has

already occurred.

Copper Sulphate (Bluestone)|precipitates|humic content

Precipitates very quickly - Copper sulphate is precipitated by carbonate hardness, accumulating in sediment at the bottom of the storage and thus rendered unavailable to control algae. In normal water the free copper ions which are toxic to algae combine rapidly with the carbonate ions and fall to the bottom as insoluble copper compounds within an hour. Chelated copper (Coptrol) by comparison is stable in hard water and remains available to be absorbed from the water by algae.

Is difficult to apply - Bluestone irritates the eyes and skin,
is very corrosive to equipment, is invasive in aircraft instruments and is hard to spread evenly from the air.

Is affected by humic content - The greater the humic
content in the water, the quicker copper is tied up and
precipitated out. Decomposing plant matter in rice crops
is thus a major limiting factor in getting results from
bluestone. Copper Sulphate also contributes to livestock toxicity problems.

Because so much copper from bluestone precipitates out rapidly as insoluble carbonates and hydroxides, copper build-up in the soil and pastures is a continuing problem. Already copper toxicity in sheep is well known in the irrigation areas especially if grazing on sub clover, or where Heliotrope or Paterson's Curse (also known as Salvation Jane, Blueweed, Purple Bluegrass, and Riverina Bluebell) is present.

COPTROL IS THE ANSWER|safe

Coptrol is a new generation algicide which is so safe it is registered

for use in human drinking water as well as in rice crops.

Coptrol offers a new approach in the prevention and control of free floating and filamentous algae in rice.

Coptrol is a special kind of organic compound in which the copper is held so tightly that it cannot be "stolen" by contact with other substances. This means for killing algae much lower quantities of copper are needed when compared with bluestone. Thus preventing copper build-up in pastures. In addition Coptrol is much more effective at killing algae. And far from being irritant and invasive, all the components of Coptrol are specifically exempt from scheduling under the Uniform Poisons Standard of the *NHMRC. *National Health and Medicine Research Council of Australia.

Coptrol is highly specific to algae and does not harm fish, plants or livestock, when used in accordance with label directions. Indeed part of the molecule is a nutrient and algae actively seek out Coptrol, which leads to their quick destruction.

COPTROL

is very stable and highly effective in controlling
algae

is a liquid and is easy to apply

is not corrosive to air craft or equipment

remains active in water longer

will not build up in the soil

Method of Application|preventative|remedial

Preventative Treatment

Since Coptrol is a non-corrosive viscous liquid it is extremely
adaptable in application. Unlike bluestone it can be Coptrol ribbon - rice page

applied as a PREVENTATIVE treatment prior to or
immediately after sowing. It can:

Piggyback with herbicide and insecticides
flown onto aerially sown or drill sown crops

Be mixed with water and dripped into water flowing into bays

Be poured from banks directly into flooded bays.

Remedial Treatment

Coptrol can also be used in these ways as a REMEDIAL

treatment for green and brown slime (which is usually blue green

algae discoloured by degenerating plant material or suspended

soil particles).

Rates of use

Situation

Pest

Application

Critical Comments

Preventative

Aerial Sown Rice

Blue-green algae

2L per 1 ha ideal

conditions for average water

depth up to 10cm

3L per 1ha for average

water depth 10-15cm

4L per 1ha when average

water depth exceeds

15cm

Apply 7-10 days after sowing as a sole spray or in tank mix with standard herbicide treatments. When applied as a sole spray use not less than 20L water per litre of Coptrol. (The effectiveness of this product depends on its concentration). Use of lower rate in deepwater will inhibit results.

Remedial

Rice:aerial and drill sown

Blue-green algae

2.5L per 1ha

Use lower rates in shallow water when algal filaments first become apparent. Use higher rates in deep water and where algal bloom is smothering emerging

rice seedlings.

Water Temperature

For best results ensure that water temperature is at least 16°C.

Compatibility

In past seasons, the use of Coptrol in conjunction with Cladophora bloom - rice page

chlorpyriphos based products, such as Lorsban, has results in compatability problems. MENTOR a compatibility agent,has been designed to overcome these problems. MENTOR should be added at the rate of 1% of the total volume mix.

Example:

In a 450 litre tank at 1% you will require 4.5 litres of MENTOR
compatibility agent. This rate will protect the two products
from reacting with each other. This gives the grower the
opportunity of flying both Coptrol and chlorpyriphos on
together.

Recommended mixing method

Add RCI compatibility agent

Add Coptrol

Add water

Agitate vigorously

Add insecticide

Coptrol Bibliography

Coptrol Frequently Asked Questions

Coptrol sales page

Coptrol Application rates

Material Safety Data Sheet

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