Commercial FAQ and General Information

Is Stylet-Oil an eradicant against powdery mildew diseases?

Based on years of University and independent research, Stylet-Oil is the best eradicant available against grape and cherry powdery mildew diseases.

What is Stylet-Oil’s mode of activity against powdery mildew?

The oil is both an eradicant and protectant against mildew and works on the basis of physical contact. The oil disrupts cell walls of the organism resulting in death within seconds of contact and by interfering with attachment of the organism to its host. 1996 research has shown that the oil prevents mildew development, kills infections both before and after they become visible and prevents sporulation. One of the many benefits of using the oil is that it can be used as an eradicant, protectant and antisporulant.

Using Stylet-Oil, can a grower control mites while spraying for powdery mildew?

Certainly. 1998 research from Cornell Extension Service has shown three pre-bloom Stylet-Oil sprays (1% at 100 gallons per acre) to significantly reduce mid-to-late season mite populations on Concord grapes. Spray for thorough coverage to the point of runoff at 1 to 2% spray concentration for mite control.

Is Stylet-Oil harmful to the environment? Where does the oil go?

The vast majority of Stylet-Oil application is broken down by microbes in the environment into carbon dioxide and water. Approximately 2% of the oil has potential to evaporate and some of the oil will bleed through the leaf cuticle.

Does Stylet-Oil fight Botrytis bunch rot? Can it be tank mixed with Rovral®, Elevate® or Vanguard®?

Yes and yes. Stylet-Oil has activity against botrytis bunch rot. Extensive testing since 1993 has shown an excellent treatment for bunch rot to be a tank mix of Rovral® at 1 lb per acre plus Stylet-Oil at 1% spray concentration. This tank mix is as effective as Rovral® sprayed alone at a rate of 2 lbs per acre. A similar performance boost occurs when Stylet-Oil is tank mixed with a label rate of Vangard® or Elevate.

  • Note: Using the oil at the 1% rate will control powdery mildew at the same time.

Can Stylet-Oil be safely sprayed post bloom on grapes?

During the post-bloom period, growers may resume a traditional sulfur program, spray oil alone, tank mix with DMI / strobilurin fungicides labeled for powdery mildew control or alternate sprays with DMI / strobilurin fungicides labeled for powdery mildew control.

Does Stylet-Oil affect the appearance of the bloom?

Yes. The "bloom" is the whitish-gray surface seen on ripening grape berries (as well as on blueberries and plums) and is caused by light striking microscopic waxy plates arranged at random angles on the berry surface. Stylet-Oil will cause these plates to lay flat so that when light strikes the berry, it does not scatter light but reflects light resulting in a shiny berry. The effect is cosmetic and does not affect the berry, pollination, taste, fermentation or disease control. The bloom will return within two to three weeks of the last oil application.

Will Stylet-Oil outperform sulfur early-season during cooler times of the year?

Sulfur needs to volatilize to be active against powdery mildew. Generally, 65˚ F is recognized as a minimum temperature required for sulfur activity against mildew. Stylet-Oil is not temperature dependent thus works as an eradicant, protectant and antisporulant 24 hours per day.

Can Stylet-Oil be tank mixed with Dithane® or Penncozeb® for control of early-season grape diseases?

Yes. The oil can be tank mixed with either Dithane® or Penncozeb® for black rot, downy mildew and phomopsis control. We recommend either product as a tank mix partner with the oil. Ziram® may be tank mixed with the oil for late-season downy mildew control.

Can Stylet-Oil be sprayed pre-bloom as a sulfur replacement on grape?

Yes. As an early-season sulfur replacement, growers should make three pre-bloom oil applications at 1 to 1.5% spray concentration at 40 to 50 GPA every 10 to 14 days. Begin spraying at budbreak or the 2" to 4" shoot growth stage. An optional fourth oil spray at bloom may be made as a tank mix with Rovral (1 lb per acre), Elevate or Vangard for simultaneous botrytis and powdery mildew control. The oil has no effect on flower bloom or pollination.

What is the spray interval between a sulfur application and a Stylet-Oil application?

On grapes, do not apply sulfur within 10 days of an oil application. On all other crops, do not apply micronized sulfur within 10 days of an oil application and do not apply oil within 14 days of an application of wettable or dusting sulfur.

Will Stylet-Oil affect wine flavor, taste or quality?

Stylet-Oil is a "Food Grade Quality" mineral oil which is colorless, tasteless and odorless. Extensive testing by University and independent researchers confirm that Stylet-Oil has no effect  on wine flavor, taste or quality.

Can growers safely tank mix Stylet-Oil with spreader/stickers?

We do not recommend tank mixing Stylet-oil with spreader/stickers or organasilicone surfactants because of the risk to destroy the oil's emulsification system. These chemicals may be sprayed separate from the oil as long as the foliage has dried. It makes no difference whether the oil goes on before or after the spreader/sticker application.

On grapes, can Stylet-Oil be tank mixed with copper fungicides?

Yes. However, do not use copper and oil together with fruit present.

Is there a simple way to determine the quality of spray coverage while spraying for powdery mildew?

Yes. because the oil kills mildew on contact, growers can use the oil as a "spray marker" to determine the overall quality of coverage.

What are some of the parameters a grower should use to successfully apply Stylet-Oil?

Regardless of the crop being sprayed or the type of equipment used to apply Stylet-Oil, successful application of the oil relies on the following parameters:

1) Stylet-Oil performance is directly related to the quality of spray coverage;

2) Apply the product in a minimum quantity of water (15 - 20 gpa);

3) Use a rate of no less than 0.5 gpa;

4) it is advisable to increase  the volume of water and Stylet-Oil as the canopy increases in size;

Can growers tank mix Stylet-Oil with Agri-Mek® and expect better mite control?

Definitely. In fact Syngenta recommends an adjuvant (such as Stylet-Oil) be tank mixed with Agri-Mek® to improve performance. Stylet-Oil will enhance the uptake of Agri-Mek® into the leaf when tank mixed at a spray concentration of 0.25% (1 qt per 100 gallons of water in the tank). However, growers will need a 1% spray concentration of oil if mildew control is required.

Can growers expect better mite control mixing Stylet-Oil with Agri-Mek® than using Agri-Mek® alone?

Definitely. In fact Syngenta recommends an adjuvant (such as Stylet-Oil) be tank mixed with Agri-Mek® to improve performance. Stylet-Oil will enhance the uptake of Agri-Mek® into the leaf when tank mixed at a spray concentration of 0.25% (1 qt per 100 gallons of water in the tank). However, growers will need a 1% spray concentration of oil if mildew control is required.

Will Stylet-Oil enhance the uptake of systemic chemicals such as Benlate®, Rally® or Ridomil®?

Yes. Stylet-Oil will enhance the uptake of systemic chemicals and improve their performance. Be sure to read all label and mixing instructions before tank mixing.

Can Stylet-Oil be used as a resistance management tool?

Absolutely. In fact we strongly urge growers to use the oil as the first treatment in a powdery mildew control program to eradicate resistant mildew strains before these strains are exposed to chemicals prone to resistance. Cleaning up an orchard or a vineyard before the first DMI or strobilurin chemicals are applied is an excellent resistant management strategy. Stylet-Oil's mode of action works at the physical level - not the biochemical level - thus the oil is an ideal material to alternate with DMI/strobilurin fungicides.

Stylet-Oil is available in what size containers?

JMS Stylet-Oil, Organic JMS Stylet-Oil and JMS Stylet-Oil for Grass Seed Use is available in the following container sizes.

  • 1 Gallon
  • 2 1/2 gallon jugs (packaged two per box)
  • 15 gallon drums
  • 30 gallon drums (not available in the Pacific Northwest)
  • 275 gallon totes

How much impurity is in 30 gallons of Stylet-Oil compared to the same volume of a 92% UR summer oil?

There are 1.2 quarts of impurity in 30 gallons of Stylet-Oil compared to 9.6 quarts of impurity in the same volume of a typical 92% UR summer oil.

Are these impurities active in biological control?

No. Mineral oil impurities are not active in biological control and perform no useful purpose other than to take up space in the container.

Are there any storage conditions which might affect quality of the oil?


  • Store the oil where water can not enter the container.
  • Stir the oil prior to use if it has been stored for a period of 1 year or more.
  • DO NOT store Stylet-Oil at temperatures below freezing.

If water enters the container during storage, can this effect the oil?

Yes. Water that enters the container has the potential to destroy the oil's emulsifier causing the oil to turn a milky color. Growers should never use Stylet-Oil if the oil has a milky color while still in the container.

When Stylet-Oil is added to water in the spray tank the mixture turns a milky color. Is this normal?

Yes. It indicates that the oil's emulsification system is working properly. When Stylet-Oil is added to water in the spray tank , the mixture should turn a milky color.

What should you do if Stylet-Oil does not emulsify (turn a milky color) when added to water?

Call JMS Flower Farms, Inc. or the dealer you purchased the oil from immediately.

What is the minimum spray temperature requirement?

Do not spray when freezing temperatures are anticipated within 48 hours of an oil application. On vegetables: do not apply when temperatures are below 50˚ F.

If applied under 90 degrees and the temperature later rises above, is there danger of injury?

No, not under normal circumstances. The temperature at the time of application is the critical factor, thus spraying should be limited to cooler nighttime or daytime periods. However, spraying stressed plants with oil (at any temperature) may result in phytotoxicity.

What type of personal protective equipment is necessary to spray the oil?

Wear coveralls, chemical resistant gloves, shoes and socks.