Tuesday, April 07, 2015

Zenith Zoysia Seed to Develop a New Oval in the Tropics - Part 4 - Maturing the Grass

It always take some time to develop an oval to the stage where it is getting ready to use.

Plants need to thicken and develop a dense sward above the ground surface while also developing their roots so they can effectively resist all the pressures on the grass that occurs during the playing of ball games or anything else planned for the oval  - it has to mature.

There will need to be regular mowing at about a 7-10 day interval - even more frequent in some cases - to help thicken the sward as lateral growth is encouraged, to fill any thin or bare spots.  Fertiliser is applied - normally at about 4 week intervals [ that is about how long normal agricultural type fertiliser can supply nutrients, particularly nitrogen, although other types [ phosphorus, potassium, trace elements] may be available for longer] for about 12 weeks,

Weed control is vital during this phase, to ensure the favoured grass is encouraged and impediments to growth removed.  Disease management and control may also be an issue in some cases.

In the period from around 45 days through to around 95 days after sowing the Zenith Zoysia area had a second application of fertiliser at about 8 -9 weeks [ 56+ days from sowing] and will be due for another at 12 -14 weeks, except this time it will be a slow release fertiliser, better suited to ongoing turf growth and with an availability period of 12 -16 weeks, thus preventing rapid growth, yet continuing to provide adequate nutrition for the turf for many weeks.

Weed control was instituted with several applications of herbicide.  The earlier applied residual herbicide continued to provide annual grass and some broadleaved weed control, but was boosted with two applications of a product that gives excellent knock down, but not very much residual weed control of broad leaved weeds - Kamba -M, applied at around 70 days after sowing and more recently at approximately 95 days from sowing.  Ideally the latter one would have been sooner, but a 48 hour dry period after application is needed for best results - and it continued to rain every few days!  Makes that a bit tricky.  The second application seems to have been very effective.

However, there have been issues with grass weeds.  While some grass weeds can be controlled with selective herbicides, the real culprit has been Bothriochloa spp plants - a particularly hard to control grass weed, and with few options for herbicide use.  The area did have a lot of these plants initially and were controlled with glyphosate before seed sowing, but the residual seed in the ground has germinated around the same time as the zoysia seed and slowly developed into a problem that requires hand removal.  The dense turf as it develops will eventually prevent most, if not all, future germination from the residual seeds, as well as the seed in the ground dying.  But in the meantime seedlings of it have to go...........  Resorting to hand weeding is almost inevitable in fine turf development, but it is labour and time intensive.  And requires many revisits to the same area to ensure it is all gone, as you can often miss small plants.

By mowing at 7-10 day intervals the weedy grass has time to put up a seed head between mowing periods, allowing easy identification, yet if removed in that 6-10 day time frame it is short enough to prevent any more seed development as full flowering has not started.  A real problem also exists in that the same species is all around the outside of the oval, and could easily re reintroduced to the oval area through mowing, especially if careless mowing of the oval surrounds is carried out.  Not an easy situation to rectify.  Although low levels are present initially, good progress in eliminating the Bothriochloa spp on the oval is progressing okay, but may require a few more weeding / mowing cycles, and ongoing vigilance.

Before mowing - 90 days from sowing

Before mowing - 90 days from sowing

Before mowing - 90 days from sowing

Before mowing at 90 days from sowing

before mowing - 90 days from sowing

After broad leaved weed control 98 days from sowing
Very effective broad leaved weed control at 98 days from sowing

At 98 days - Bothriochloa spp - grass weed in dense Zenith zoysia turf - note emerged seed head 7 days after mowing

No comments: