Fungal diseases can reduce the quality and yield of many agronomic crops, including grape, tree fruit, grass seed and vegetable crops. Until now, fungicides available to growers have worked primarily at the biochemical level making them prone to chemical resistance from repeated application. Chemicals which work- ed at the physical level ― notably sulfur ― had to be sprayed as protectants, limiting their usefulness  under heavy disease pres-sure.

Stylet-Oil brings to growers a new dimension for disease control. Not only does the oil work at the physical level (meaning there is practically no chance for resistance to develop) but the oil acts as both an eradicant as well as a protectant against powdery mildew diseases. Stylet-Oil has demonstrated broad spectrum activity against many ecto-parasitic fungi, including powdery mildew, rust, Alternaria, gummy stem blight and Botrytis.

Recent research (1996) by Dr. John Northover and K. E. Schneider (Plant Management Research Centre, Ontario, Canada) shows Stylet-Oil to have four distinct physical modes of action as a fungicide against grape powdery mildew:

• protective (prevents disease before inoculation and infection)
• pre-lesion (suppresses an infection before it occurs)
• post-lesion (deactivation of a visible infection)
• antisporulant (may result from curative treatments made either before or after lesion appearance)

Stylet-Oil has excellent eradicant activity against powdery mildew diseases and will kill  powdery mildew within seconds of contact. In addition, depending on the use rate, Stylet-Oil will prevent powdery mildew development for 10 to 14 days.

The Need For Quality Spray Coverage:
Because Stylet-Oil works on the basis of physical contact, the performance of the oil is directly related to the quality of the spray coverage. Many grape growers have witnessed this effect first-hand when spraying the oil on severely infected grape. Since the oil kills mildew on contact, Stylet-Oil can be used as a "spray marker" to determine the quality of the spray coverage. This relationship is expressed in a simple equation:

Remember:   50% Spray Coverage  = No More Than 50% Kill

Thorough coverage of fruit bunches and foliage is necessary for optimum performance. To enhance thorough spray coverage ―

• maintain a constant tractor speed
• if necessary, remove excess foliage during the season so the spray can reach fruit bunches
• check nozzles for wear before and during the season. Replace worn nozzles when they eject 10% more gallonage than new nozzles
• spray every row, never alternate rows
• do not spray when wind speed exceeds 10 mph or apply the oil to wet foliage
• vary the volume of dilute spray according to the size / density of the spray target
• spray to the point of runoff

Method of Application
Type of sprayers used to apply Stylet-Oil as a fungicide: 

• orchard or speed sprayer
• air assist
• hydraulic boom sprayer
• Kinkelder electrostatic

Spray Pressure: Spray pressure may vary depending on the type of sprayer used. Generally small spray droplets provide better spray coverage (i.e., protection) than larger droplets. However, when using air assist sprayers, small spray droplets injected into a rapidly moving air stream are prone to evaporation before contact with the target. For this reason growers should strive to find the "sweet spot" that maxi- mizes coverage but minimizes evaporation of spray droplets. Note: We do not recommend low volume electrostatic sprayers or mist blowers to apply the oil because coverage will be com- promised from lack of dilute spray volume. NOTE: Reducing the size of the spray droplet by one-half results in 8 times more droplets to impinge on the target (see graphic).

Tractor Speed: Tractor speed may vary depending on the type of crop or sprayer used for application. Adjust tractor speed to achieve spray coverage to the point of runoff. On large fruit trees the tractor speed may be 1 to 2 mph; on row crops it may be 3 to 4 mph.

Constant Agitation: Use either mechanical or bypass agitation in the spray tank to insure the oil remains an emulsion in the tank. Never leave a spray tank mix of oil + water overnight to be sprayed out the next day.

Application Rate And Spray Frequency
Spray Concentration: Rate may vary depending on the pest or crop ― consult the current label. Use a higher spray concentration when disease pressure is moderate to high and the label specifies a concen- tration range (such as 1 to 2%).

Gallonage: Gallonage may vary depending on the pest or crop ― consult the current label. From 25 to 150 gallons of dilute spray emulsion per acre depending on plant size. Growers should adjust gallonage according to the size / density of the spray target to achieve thorough coverage to the point of runoff. Gallonage should be adjusted by:

• adding or removing spray nozzles
• changing the nozzle orifice size
• on large tree fruit / nut crops, by adjusting tractor speed

We do not recommend adjusting spray pressure to vary the gallonage as this will affect the size of the spray particle.

Spray Frequency: Spray frequency may vary depending on the pest or crop ― consult the current label. Use a shorter spray interval when disease conditions are severe. Stylet-Oil may be used to prevent certain fungal diseases or as a post-infection (eradicant) spray after infection has occurred. However, taking the necessary steps to prevent a problem has more merit than reacting to disease after it has occurred. This may mean growers will be spraying when disease symptoms are not visible, but that is the basic concept behind spraying oil as a fungicide in an oil prevention program.

Re-entry Interval ― The re-entry interval (REI) of Stylet-Oil is 4 hours.
Residue Tolerance ― Stylet-Oil has no residue tolerance level.
Pre Harvest Interval ― There is no pre harvest interval.