New Duckweed Water Treatment System Installed at Wickham

A new duckweed barrier water treatment system was installed for WA Water Corporation at Wickham in the Pilbara in mid June 2007, with the duckweed itself to be placed on site in July.

This is part of a serious evaluation of the concept for use in warmer areas of Australia where duckweed thrives year round.

The barriers provide the ideal still water conditions for duckweed growth in sewerage lagoons where there is adequate nutrients, plus plenty of sun, for growth. The duckweed aids in the elimination of the algal growth in the effluent which currently impacts effective reuse of the effluent for irrigation.

Currently the TSS level in the pond is very high [mainly algae], and it is expected that this will fall dramatically as duckweed growth accelerates and covers the pond. Reduction in bacterial levels are also expected, along with small reductions in nutrient levels [ which are still of benefit in most agricultural water reuse situations].

The photos are of before and after installation of the barriers. These systems significantly "quiet the water" , even with very windy conditions and allow for adequate growth of duckweed. Wind at the time of these photos was around 30km/hr.

Drip Irrigation Boosts Pineapple Yields by 21% Over Conventional Sprinklers

An irrigation trial in pineapples at Yeppoon, Qld, has recorded a 21pc lift in production, using a drip irrigation system compared with a conventional overhead irrigation system.

These results, from a trial commenced in 2005 on the Steven's property near Yeppoon, were presented to growers at a field day organised by Fitzroy River and Coastal Catchments and Growcom Water for Profit Field Officer, Marcus McCormick.

Two equal sized and similar production blocks of about a quarter of a hectare each were selected to compare the yield and water efficiency benefits of drip irrigation with an overhead system.

The infield material costs of the drip line worked out at $3,516/ha compared to $1,932/ha for the solid set overhead system - so drip cost more. “However, while the in-paddock costs for the dripline were almost double that of the overhead, installation required less labour," Mr McCormick said. "And the drip system provided significant yield and profit benefits which more than made up for the expense.”

There were also remarkable differences in the volume of irrigation water used, with dripline saving about 50%. Only 0.489ML of water was applied to the drip block throughout the whole of the trial compared with 0.892ML for the overhead block. "We installed an Enviroscan to monitor soil moisture levels and this assisted the Stevens in making appropriate decisions about when to irrigate,” Mr McCormick said.

From this water, an additional 1,042 trays per ha of pineapples were harvested on the drip irrigation block. This represented a 21pc increase in production.

A cost analysis of the trial was conducted using pack-out figures supplied by the Stevens family and average market prices for the first six weeks of 2007 supplied by Tropical Pines. Based on these figures, the extra production from the drip block represented an additional 16pc in returns, after the cost increases for the in-paddock setup of the drip block had been accounted for.

Improved uniformity of fruit quality, sizing and superior growth and vigour of the pineapple plants produced from the drip block were apparent in the trial. Drip irrigation also allowed superior irrigation scheduling. “The beauty of drip irrigation is that the wind does not affect when you can irrigate," Nathan Stevens said at the field day. "At times, we had to wait for up to a month until we could irrigate with the overhead because of the wind,” The trial has attracted a great deal of interest from the pineapple industry.

The trial was the result of a collaborative partnership between the Stevens family, Tropical Pines, Fitzroy River and Coastal Catchments Inc., Growcom’s Water for Profit team, Yeppoon District Co-op., Plastro Asia Pacific, Menkens Irrigation Services and the Fitzroy Basin Association. A second stage of the trial is expected to look at the production benefits associated with using fertigation and chemigation through drip irrigation to manage plant nutrition and health.

Once again, water efficient irrigation systems do not cost.............they really do improve the bottom line while saving water.

Is Your Couch or Zoysia Declining?

Summertime Blues: Couchgrass Decline (Part I)

While damage to couch is more prominent, especially in the USA - due to the sheer preponderance of the species on fine lawn areas - damage on zoysia, and other warm season turf species is probable, both there and elsewhere in the warmer regions of the world.

In many parts of the northern Australia and areas of South Africa couchgrass (Cynodon spp.) has suffered greatly this past summer, and symptoms may persist into autumn. Several reasons or causes have been given, but one prominent reason is – and I will use the U.S. term - bermudagrass decline. The first reported description of bermudagrass decline occurred in the southeastern United States (i.e. Florida).

Under hot humid and frequent rainfall, patches would develop on the turf and quickly coelesce forming larger non-descript areas of turf loss. The root systems turn black and die back is significant. Although, environmental factors like low light, and saturated soils no doubt contributed to the decline, the pathogen Gaeumannomyces graminis var. graminis was identified as the cause.

Originally bermudagrass decline was only associated with bermudagrass. However, patch diseases caused by the same fungus, G. graminis var graminis have now been reported on most of the warm season turfgrasses. To reflect the increasing number of turfgrasses that are infected, the name has been changed to be more encompassing by calling these root diseases of warm season turfgrasses, “Root Decline of Warm- Season Turfgrasses” (Smiley,et al. 2006).

In the United States, where kikuyugrass (Penisetum clandestinum) is limited to southern California, a patch disease similar to bermudagrass decline has been reported.

[As a side-note, and one based on my opinion with no data to back it up, I wonder if some of the problems this past summer on kikuyugrass may have been due to this pathogen or one closely associated with it? - Henk Smith, Syngenta.]

[ From Syngenta, 6 June 2007]

Watch this space..............more to come as the story unfolds further. This is of particular interest to tropical north Australia!

In the USA, this disease seems to occur most often on intensively managed 3- to 6-year-old turfs, with many of the ultra-dwarf varieties prone to infection. Excessive nitrogen fertilization, potash deficiency, sharp increases in soil pH, and thatch accumulation increase turf susceptibility to attack by the causal fungus. Low maintenance bermudagrass lawns usually have little trouble. The disease is found on all bermudagrasses but is most damaging on the newer hybrid varieties.

Exceptionally low mowing heights, poor drainage, thatch accumulation, and high soil organic matter content have been linked with the occurrence of bermudagrass decline on greens and tees.

The causal fungus of bermudagrass decline is Gaeumannomyces graminis var. graminis. Related fungi, Leptosphaeria korrae and Ophiosphaerella herpotricha, have been shown to be related to the problem in other parts of the United States.

The same organism, Gaeumannomyces, is the fungus associated with take-all patch in St. Augustinegrass.

Initial symptoms of bermudagrass decline include chlorotic patches of turf 20 - 60cm in diameter. The turf thins out and may eventually be completely killed in these patches. Chlorotic leaf blades may develop next to green shoots at the margins of the diseased area. Roots of diseased bermudagrass are brown and without feeder roots and root hairs. Signs of the fungus on the root surface appear as dark brown hypal runners. The disease occurs on weakened or damaged turf which indicates that management could be the key to control.

If disease occurs, try to identify the predisposing factors and correct them through proper management practices. On golf greens, cricket wickets or other very low cut areas, simply raising the mowing height is the most effective management practice to correct the problem. Some fungicides are effective for the control of bermuda decline caused by Gaeumannomyces graminis. Since infection is thought to occur primarily in autumn, with disease progression continuing into the winter months under cool moist conditions, autumn or end of wet season applications may be the best time for fungicides to be applied for preventative purposes. The efficacy in controlling the already established disease may be disappointing.

For more information and assessment please contact us .