North American Fruit Explorers mailing list at ibiblio

[<dmnorton@royaloakfarmorchard.com>]

Mark,

98% paraffin petroleum based oils are normally derivatives of paraffin-based petroleum oil. Crop oils are generally 95 to 98 percent oil with 1 to 2 percent surfactant/emulsifier. Crop oil concentrates are a blend of crop oils (80 to 85 percent) and a nonionic surfactant (15 to 20 percent). The purpose of the nonionic surfactant in this mixture is to emulsify the oil in the spray solution and lower the surface tension of the overall spray solution.  It typically has about a 7 to 14 day residual.  For every 1" of rain you get after spraying, you will loose approx. one day of residual value. Do not apply oils if plant tissues are wet or rain is likely because if it rains before the oil dries on the leaves, the rain will usually wash the oil away and make re-spraying necessary.

I am sure you know the ideal time to spray is on a cool, cloudy morning when there is no wind and the temperature is between 40º and 90º. The spray should dry before direct sun falls on the trees or before freezing occurs.  These conditions inhibit oil evaporation. High humidity (above 90 percent) also may contribute to injury risk, while low humidity generally reduces it.  If your trees are under attack by a heavy insect infestation while the weather is uncooperative, particularly while it is too hot, spray them with water to knock off as many pests as possible, then wait for more favorable conditions.  Just some thoughts....hope they help!

 

Dennis Norton
Royal Oak Farm Orchard
http://www.royaloakfarmorchard.com
http://www.theorchardkeeper.blogspot.com
http://www.revivalhymn.com

----- Original Message -----

From: Mark & Helen Angermayer

To: North American Fruit Explorers

Sent: Monday, March 10, 2008 9:48 PM

Subject: [NAFEX] Dormant oil question

I'm about ready to apply dormant oil and wondered if it's considered a rainfast product? (Label doesn't say)  If so, how long does it have to be on the tree before it's rainfast?  Does rain reduce the residual effect?   

 

Tomorrow's supposed to be clear, but every day after there's a chance of rain in the forcast.  Should I go for it tomorrow, or would the rain the next few days just wash it off?  The product is a 98% parrafin petroleum based oil.

 

Thanks,
Mark

KS