2 4 D question

[arkcowman]

It seems someone told me 2 4 d requires cool weather application. Is this correct ? If yes, how hot is too hot to prohibit application ? If not 2 4 d what do you use for pasture weed control during hot (90's +) weather ?
I'm in North Mississippi. Also experiencing some rain shortfall.

 

[dyates]

I don't think the cool weather itself is the requirement. In order for most chemicals to work, the stomata, pores in the leaves, must be open for intake. Those pores close during hot days to reduce moisture loss. I wouldn't hesitate to use 24d during hot weather, but it will be more effective if you apply it late in the evening as the pores will open at night.

 

[Farmgirl]

There are at least two types of 2 4 D. 2 4 D Amine should be used in hot weather. 2 4 D Ester is to be used in cool weather. I learned that last year when we did some spraying.

Farmgirl

 

[Phil in Tupelo]

I am not an expert, but I think 24D in Mississippi is a restricted use pesticide. If spraying in hot weather it may vaporize and can drift as much as a mile or more. Cotton, tomatoes and some yard turfs will almost die if you just bring an unopened container of the stuff around, they are that sensitive to it. I don't think you can use it either after April 15 or May 15 (cotton is up). If you spray your pasture now and it drifts and kills your neighbor's cotton or tomateos or some yard plants you likely will get to pay for the damages. Call your county agent and they can get you advice more acceptible to your area.

 

[MikeC]

Important Characteristics of 2,4-D
Volatility - volatility refers to the tendency of a chemical to vaporize. Vapor drift is the movement of herbicide vapor off-target. The level of volatility of a chemical is related to the compounds vapor pressure. The amine and sodium salts of 2,4-D are generally considered to be of minimal volatility hazard. Ester formulations, however, are volatile compounds. Most current, commercial 2,4-D ester formulations are termed "low-volatile", but keep in mind that they remain potentially volatile compounds. Under hot and humid conditions the volatility hazard increases. Consequently, extreme care should be taken when applying 2,4-D and other hormone-type herbicides.

Salt Formulations - amine salts are the most commonly used form. The amine salts of 2,4-D are not considered volatile; however, windy conditions can cause physical drift of the herbicide onto susceptible plants. Most amine salts readily dissolve in water to form clear solutions.

Ester Formulations - esters are essentially insoluble in water. The ester is diluted in oil with an emulsifying agent added. When mixed with water, the emulsifier keeps the tiny oil-like droplets suspended, much the way butterfat is suspended in milk. When mixed with water, the 2,4-D emulsion appears milky colored. Ester formulations are generally considered to be slightly more active than the salt formulations and are more susceptible to volatility.

 

[msscamp]

It seems someone told me 2 4 d requires cool weather application. Is this correct ? If yes, how hot is too hot to prohibit application ?

At the risk of sounding snippy - if all else fails, read the directions. Every herbicide comes with a little booklet attached to the front of the bottle that tells you how much to apply, under what conditions to apply it, and what the temperature restrictions for application are.

 

[Jogeephus]

Both will work during hot weather but as Farmgirl pointed out they can vaporize and "walk" on you. Amine will not walk as easily as the Ester. Safest thing is not to spray near cotton on a hot humid day. So if you got to spray next to a sensitive area like a cotton field, don't use the ester. Don't spray the amine unless the temp and humidity added together is less than 120 - some use 150. Do use as little pressure as possible and by all means don't spray on a windy day. Cotton - or maters - don't like it at all.