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Do you know that...

- the HARDI TWIN sprayer can give you up to 50% more hours available for spraying?

In the diagram below you can see the number of hours available for spraying in the spraying season. The only differences between conventional and TWIN sprayers is that with the conventional the wind speed limit is 4 m/s where you with the TWIN can accept 8 m/s.

Spraying hours in 2000-2003 (Aarslev, Denmark).

twin-fact-optimum_hours.gif

Conditions for minimum 3 consecutive hours /day 

- Temperatures day min. 1°C and min. up to 10°C, night > 1°C 
- Rain < 0.1 mm/h, and < 2 mm from 3h before till 6 h after spraying. 
- Relative humidity 50-95% 
- Maximum wind speed: Conventional 4 m/s - TWIN 8 m/s

 


 

Optimal field timing

Spray drift from conventional sprayer can be so great that the operator has to stop before having the spray job done. With efficient drift control it is much easier for the operator to be able to spray the entire field with optimal timing. Under most conditions the farmers get up to twice as many hours for a safe and efficient spray job with the TWIN sprayer compared to conventional spraying.

twin-fact-optimum_hours-b.gifWhen spraying for weed, fungi and insect control, the highest effect is gained when spraying the pest at the most vulnerable stage. Field timing is the key to getting the best biological effects and is the most secure route to reduced doses. 

Herbicide doses can often be reduced considerably if the target weeds are at the cotyledenous stage – a difficult challenge since only a few days are then available. 

These few opportunities to spray are limited with conventional sprayers because of wind or losing time hauling large water volumes to the field. TWIN sprayers increase possibilities to spray in higher winds and gain maximum spraying time in the field too. 
As a "rule of thumb" you can for the most ordinary crops roughly define following spray “windows”, i.e. the time at disposal in order to ensure a quality result with the lowest possible dosing.


-Cereals: 5 - 6 days
-Sugar beets: 2 days
-Potatoes: 1 day

Compared with the size of the area of the various crops the above gives a good hint of the necessary capacity. In this connection another consideration is to be taken: how often do you have to spray simultaneously in various crops at the optimum spraying time.

 

- with HARDI TWIN you can get FULL control with REDUCED chemical dose?

Grass weed can be difficult to control especially when using coarse drops. The movements in the plants caused by the air assistance and the fine droplets secure a high deposit on the grass weed. Higher deposit on the target increases the efficacy, which makes it possible to reduce the chemical dose rate.

twin-fact-reduced_dose.jpg

Control of Loose Silky-bentgrass (Apera spica-venti)

- Nozzle: ISO FF/LD 110 015 @ 2 bar, INJET 110 01 @ 4,7 bar
- Volume: 100 l/ha
- Driving speed: 6 km/h
- Herbicide: Primera Super (Fenoxaprop-P-ethyle) 1 l/ha = 3/3 


In the above test the HARDI TWIN at 1/3 of the dose has been just as effective as other techniques at full dose - or you could use 2/3 of the dose and get an even higher efficacy.

 

- HARDI TWIN can be used at higher spraying speeds without increasing drift?

Farmers around the world exploit faster spraying speeds to obtain higher capacity. Going up in spraying speeds increases the drift cloud behind the sprayer on conventional sprayers. 


twin-fact-faster_spraying.jpg
Kappel and Schulze-Stentrop, 2003

Total drift - relative measurement (conventional spraying @ 15 km/h = 100%)

Nozzle: FF025 110 
Pressure: 2 bar 
Water volume: 160 l/ha (6 km/h), 110 l/ha (9km/h), 65 l/ha (15 km/h) 
Wind velocity: 2-4 m/s   

 


 

The active air assistance forces all the drops from the nozzle - down onto the target surface and through crop canopies when needed – to both avoid drift but also to secure an even distribution in the complete width of the spray swath.

twin-fact-faster_spraying-b.jpg
Cooper and Taylor, 2000

Distribution measured underneat the boom - comparison of HARDI TWIN and conventional sprayer

 



Sprayers are getting bigger and going faster. These trends with conventional sprayers are causing drift concerns, poorer distribution and raising residue fears in high value crops. Poor distribution in the field will effect chemical performance, can cause crop damage and will risk yield loss. 

 

TWIN sprayer users will not have these fears.

 

- HARDI TWIN is minimising the loss on the ground and increasing the on-target deposit?

When moving the spray cloud down into the crop with huge amounts of air you could fear that most of it would end up at the ground - this is however not the case.

In the test below plants where cut into pieces after spraying and the amount of depositet chemicals where detected and compared with conventional spraying.

Change of the deposit by using HARDI TWIN

  Air Backward Air Forward twin-fact-Deposit_position.jpg
Ear
 
-1 +46
 Top Leaf
 
+43 +61
 Top Stem
 
+11 +31
Lower Leaf 
+ Lower Stem
 
+101 +14
 Ground
 
 -41 -66 


As an example +43% on the top leaf means that the plant sprayed with the TWIN has got 43% more deposit than the conventionally sprayed plants. The result from these tests shows that angling either forward or backwards reduces the loss on ground with 40 - 70%. This is due to the higher "filtering effect" from the crop when the spray hits at an angle - compared with the fact that the TWIN air moves the plants in the spray swath so they are able to catch more of the spray.

 

- with HARDI TWIN you can spray under sub-optimal wind conditions and still get an optimal result?

As an example +43% on the top leaf means that the plant sprayed with the TWIN has got 43% more deposit than the conventionally sprayed plants. The result from these tests shows that angling either forward or backwards reduces the loss on ground with 40 - 70%. This is due to the higher "filtering effect" from the crop when the spray hits at an angle - compared with the fact that the TWIN air moves the plants in the spray swath so they are able to catch more of the spray.

twin-fact-wind_speed.jpg
Taylor et al. 1989

Air borne drift - TWIN and conventional
Water volume: 100 l/ha
Driving speed: 7.7 km/h
Spray pressure: 2 bar
Nozzle:  ISO F-110 - 02 

With the HARDI TWIN sprayer this development in the drift curve seems to be delayed - and at 8 m/s there is not more drift than with 1.5 and 3 m/s for the conventional. It is therefore possible to spray at much higher wind speeds and still get the same good result.