6 September 2002

How to get the best from novel grassweed killers controller

In the first of a fresh

series of baseline articles,

we find out how to get

the best from Crystal

or Ice (flufenacet +

pendimethalin) herbicide

FOR good results on difficult blackgrass and ryegrass Crystal users must observe a few simple application rules, says manufacturer BASF.

The first point to remember is to use it at the pre-emergence timing, advises the firms technical business manager Rob Gladwin.

"That means within 10 days of drilling. If the crop is germinating, you can be sure that the blackgrass is too.

"As soon as you have drilled, the clock is ticking. That may mean prioritising fields, making sure that you drill difficult areas last and then fitting in spraying. At emergence, its not uncommon for blackgrass to beat wheat out of the ground."

Mr Gladwins also advises using 4 litres/ha dose. "Dont go down to 3 litres/ha or you may well be disappointed with the results. The extra litre makes quite a difference."

Seed-beds are important, as is depth of drilling, he adds. "If the crop is shallow drilled and seed-bed conditions are bad, then theres always a chance that youll affect the crop."

Drilling depth needs to be a minimum of 32mm and clod size must be less than 3cm. "You need a good tilth and the seed must be covered up.

"Dry, cobbly power harrow beaten seed-beds arent going to give the best results or maintain crop safety, nor are compacted seed-beds."

Last year, the first of commercial Crystal use, drilling depth proved more critical than the type of drill used, says Mr Gladwin. "The issue is to make sure you drill to a reasonable depth."

The interval between pre-emergence application and the follow-up post-em spray must be tight. "Go on again as soon as the blackgrass is through."

Where a Stomp/Lexus (pendimethalin/flupyrsulfuron-methyl) mix is intended as the follow-up, it should be applied no later than the weeds two true leaves stage. "Once blackgrass gets to the three true leaves stage, it starts to tiller and control will be reduced. Dont wait for it to recover from the pre-em treatment. Hit it again while it is vulnerable."

This particular follow-up programme has given the best results in trials, he adds.

For ryegrass, the timing message is the same, but the products applied post-em will be different. "Chlorotoluron used alone has done well, but the addition of Stomp will be needed with high or problem populations."

Using Crystal will cost about £32/ha (£13/acre) and should give 70% control of blackgrass, says Mr Gladwin. "In combination with other control measures, it has a major role to play with difficult blackgrass and ryegrass.

"Many growers wont have the same experience of resistant ryegrass as they do with blackgrass, but the key points are the same."

1 Timing Use pre-em, spray as soon as possible after drilling and ideally within 10 days.

2 Rate BASF recommends 4 litres/ha, but distributors believe 3 litres/ha sufficient if timing is good.

3 Seed-bed conditions Clods must be less than 3cm, a good tilth is required.

4 Drilling depth Drill to a minimum depth of 32mm. Seed must be buried.

5 Crop damage Occurred only with shallow drilling and poor seed-beds last year. Heavy rainfall after application can make it worse.

6 Follow-up spray Keep interval tight for blackgrass. Spray again by two true leaves.

7 Brome control Makes a good start to brome control programmes, especially sterile brome.

8 Annual meadow grass Use 2 litres/ha and mix with IPU, spray at 2-3 leaves.

9 Ryegrass Excellent results on resistant ryegrass with 3 litres/ha, follow-up with CTU or CTU/IPU.

10 Cost About £32/ha for 4 litres/ha.

Careful attention to seed-beds and drilling depth is important to allow flufenacet-based products to work well and avoid crop damage.

Ice advice from the distributor

Drill and spray is the advice from Dalgetys technical manager Bob Bulmer, when it comes to using Ice – the trade name for Crystal marketed by Dalgety.

"Spray as soon as youve drilled," he says. "It doesnt need much moisture to work and theres a steep decline in control as application is delayed."

Seed-bed conditions are important and any resulting crop damage is made worse by heavy rainfall after application, says Dr Bulmer.

"Cloddy seed-beds are out and the seed must be well buried. A key decision with the use of this product is whether the seed-bed is suitable."

Ice is a good start for brome control programmes, especially sterile brome, as well as being the best choice for annual meadow-grass, he adds.

"And weve had fantastic results on resistant ryegrass. In one trial we had 100% control from a single application.

"But as ryegrass germinates over a longer period than the other grassweeds, its important to follow-up with chlorotoluron or a CTU/IPU mix."

For blackgrass and brome, he recommends a rate of 3-4 litres/ha. "The 3 litres/ha rate is adequate where your spray timing is good. And 3 litres is enough for ryegrass."

For annual meadow grass, the advice is different. "Apply Ice at 2 litres/ha post-emergence, at the two to three leaves stage, and include a low dose of IPU."

Dr Bulmer believes that Ice is better on blackgrass, ryegrass and annual meadow grass than the alternative pre-em herbicides. "Only where there are mixed populations of wild oats and blackgrass would I advocate switching to Avadex." &#42