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Ontario, Canada.

Have you ever had trouble controlling a pest with a pesticide? You may have thought that the problem was due to the rate used or pest resistance, or maybe the chemical itself. Did you ever think to check the pH of the water used to mix the pesticide? The pH of the water that goes into your spray tank influences how effectively many pesticides and growth regulators work.

10/23/2006 12:28:06 PM

Ctpumpkin@optonline.net

Alkaline spray water can render some insecticide useless in mere minutes so this is a valid concern. Triclorfon is a good example.

10/23/2006 2:38:35 PM

valparaiso, in

what level of pH in the water should we be looking for?
Gritch

10/23/2006 8:37:12 PM

Ctpumpkin@optonline.net

For some insecticides I would be concerned with anything over 7.5 especially if the mix was going to stand for over 30 minutes.

10/23/2006 10:42:05 PM

Ontario, Canada.

Water quality is one of the most often overlooked & little talked about factors in IPM. Depending on the specific chemical properties of the pesticide, the pH of the mix water and the length of time that the pesticide is in contact with the water, the breakdown can happen relatively rapidly. The determination of correct Ph levels is not the same for all control products. It is best to consult the manufacturer. Generally ranges of 5.5 to 7.0 are safe for most products. These levels also enhance the solubility of most micronutrients when used in combination.

10/24/2006 4:47:27 AM

Ontario, Canada.

Table 1
Half-life of pesticides at varying pH values.

Active ingredient pH 6 pH 7 pH 8 pH 9

Azinphos-methyl 10 days 12 hours
Captan 8 hours 10 minutes 2 minutes
Carbaryl 100-150 days 24-30 days 2-3 days 1-3 days
Carbofuran 200 days 40 days 5 days 3 days
Chlorpyrifos 35 days 22 days
Diazinon 70 days 29 days
Dimethoate 12 hours 1 hour
Disulfoton 32 hours 7 hours
Malathion 8 days 3 days 19 hours
Methomyl 54 weeks 38 weeks 20 weeks
Phosmet 12-24 hours 4 hours
Parathion 17 weeks 29 days
Propargite 331 days 1 day
Trichlorfon 4 days 6 hours 1 hour

10/24/2006 4:48:58 AM

President - GPC

So if we adjust the PH prior to mixing we can expect better or should I say longer effective periods. I would adjust the PH with a basic freshwater fish hobby PH kit. Is that correct?

10/24/2006 8:51:04 AM

Ontario, Canada.

Yes, proper Ph will increase the effective period of most pesticides if you have been using incorrect Ph levels in your tank mix. Adjust by what ever means. Keep in mind that some adjuvants also may change Ph and or respond to differently as well. When in doubt Google is only a search tool bar away.

Russ

10/24/2006 2:51:05 PM

President - GPC

Thanks Russ, good post

10/24/2006 3:12:53 PM

Ctpumpkin@optonline.net

Citric acid is often sold & used to buffer tank water but years ago we used phosphoric acid. Having a properly buffered tank mix also increases plant safety.

LOL...Reminds me of a story...I'll never forget this newb we had working for us...He left 500 gallons of a Urea based fertilizer sitting in his spray tank over the long July 4th weekend. The following Tuesday his truck stank bad of ammonia. The boss tested the tank & the pH obviously needed correcting. The pH was "off the chart" low. The kid drew off 3 gallons of straight phosporic acid & climbed up on top of the truck....Now the veterans all knew enough to put on a full face shield, apron, gloves, etc when doing this but the yahoo jumps up real quick trying to get rolling. We all start yelling & he reluctantly jumps down all huffy like & puts the safety gear on. While he's dressing I tell him to pour the acid in very slowly since the stale brew smelled bad & would surely start boiling...But old fast boy knew better...He jumps up on the truck & dumps the whole 3 gallons in all at once. The resulting explosion showered the entire shop with acid & liquid fertilizer. Knocked the face shield & the idiotic smirk right off his face. If we hadn't been so worried about his facial burns I'm sure one of us would have clocked him good.

10/24/2006 11:43:27 PM

Ctpumpkin@optonline.net

Excuse me...that should have read "off the chart" HIGH!

10/24/2006 11:44:35 PM

Montoursville, PA

Very good heads up. There is rarely a summer when something like this does not show up. Hospital reports include severe burns through absolute loss of eye sight.

10/25/2006 8:32:48 AM