11/6/2012 - By Matthew Shultz

With much of EOP in full swing, nurserymen are making many decisions of how much and what type of chemistry to purchase for the upcoming year. With chemical prices seemingly higher than gold, nursery operators need to be getting the most bang for their buck. Each day I see nurserymen making some sort of error or  taking an inefficient path with their chemical program. The following should provide some helpful tips in avoiding those mistakes. As this list is quite long, it will be split into two parts.

1)      Follow the label: This seems reasonable enough, but is often ignored. Chemical manufacturers have gone through a great deal of testing to see whether certain varieties of plants can handle certain chemicals. This is not always foolproof. If you are uncertain, do your own trial - say 100 plants. Of course you also want to stay legal. REI’s, greenhouse or outdoor field grown and chemical rates are all there.

Always a good idea to ask a “consultant” or fellow nurseryman whether they have successfully applied a certain product to a certain plant variety. I often hear, “ I have been doing this for 30 years and never had a problem”. Well there is a first time for everything!

2)      What time should I spray?  The best time is between 6 am and 10 am. Afternoons tend to be when plants have stressed after a full day of heat and sun. The wind usually isn’t as bad in early morning and this will control any unnecessary drift. Leaf temperatures in the morning are usually at their coolest. In large nurseries, this may be unfeasible, but do your best. Sometimes applicators can be busy applying drenches as temperatures rise, or applying pre-emergent herbicides.

3)      Disease spray rotations: I could write an entire newsletter on this. Sometimes growers will use the shot gun approach on a disease and use everything in the chemical shed, but the disease wins the battle. First, it is important to have the disease properly identified through a pathology lab. The UF Plant Disease Clinic in Gainesville provides very reliable results. If it is a common pest to that plant, it can often be identified in the field, although even the most seasoned plant scout can make a mistake there. So if in doubt, test. By knowing the pathogen, you can use those fungicides that have the best efficacy on that pathogen. Using too many chemicals can distance the better fungicides from the lesser ones. Be sure to rotate your chemistries to avoid resistance.

4)      Spray water pH:  Most pesticides are more effective in acidic spray water. The pH levels for each are variable (and there are charts that provide more information), but 5.5 to 6.0 seems to be the target to reach overall. Some of the complex compounds in pesticides become unstable in high pH water. Harrells pH buffer or Indicate are two recommended buffers, however adding 3-4 ounces phosphoric acid  per 100 gallons of spray water will often do the job. Labs can do titrations of your spray water and give you the exact amount of acid to add. They will often need a sample of your acid type as well. Nutritional sprays are often acidic in nature, such as 20-20-20 or Epsom salts so no acid or buffer needs to be added.

5)      Mixing chemicals: some growers are very creative with their spray mixes. They want to kill 5 birds with one stone. Ask your consultant or refer to compatibility charts if you are uncertain. Just because a spray cocktail does not burn, does not mean you have not reduced the efficacy of chemicals by mixing them. I like to keep nutritional spray packages from pesticide packages. Some mixes seem to have a synergistic effect such as Daconil + T-methyl or an Imidacloprid + Acephate. Ask around and try not to make too many Long Island Ice Teas in your spray tank.

6)      Scouting: This is imperative to formulating an effective spray program/schedule - catch those pests before they spread. Chemical applicators make good scouts, as they know what they are looking for. Remember that some pests are seasonable such as Phytophthora in summer or Southern blight in fall. Keep records from years previous, as pests are often right on time.

7)      Mixing Order: 

S – Suspension – SG (Soluble Granules), SL (Soluble Liquids), WDG etc

A – Agitation – add agitation to the tank at this point

S – Solutions – Products that dissolve completely (soluble fertilizers)

E – Emulsions – Oil based products

*Stay away from mixing 2 products that are supposed to dissolve in solution. Again the label is the law so always consult it before mixing products together, and test a small portion of the crop!

 The November Newsletter will start where I left off - spray, sprench or drench. Hate to leave you hanging!