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?
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)
COPTROL IS THE ANSWER
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.
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
Since Coptrol is a non-corrosive viscous liquid it is extremely adaptable in application. Unlike bluestone it can be 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 waterflowing into bays
Be poured from banks directly into flooded bays.
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
In past seasons, the use of Coptrol in conjunction with 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.
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