12/11/2012 - By Harrell's

Well I have had hundreds of calls requesting we put out the latter half of our 2 part “Spray Tips Series”, so here it goes.

SPRAY, DRENCH OR SPRENCH? - Which should I do? Well spraying is simply defined as dispersing the chemical through the air onto the foliage of the crops in need. This includes nutritionals, miticides, insecticides, fungicides and herbicides. It is meant to provide a uniform coating on the leaf surface, to ward off foliar pests or to mainline nutritionals for foliar absorption. The term sprench was a result of modern pop culture, defining a hybridization of a spray and drench, and is essentially a heavy spray directed at the base of the plant. This is done to prevent crown rots, diseases that occur right at the soil line or on recently planted cuttings or liners that have not rooted down yet.

The drench is often done with a wand versus a hand gun and is meant to direct the pesticide or/and nutritional to the root system. Often times plants are drenched right after being “bumped up” from a smaller pot size. Typically a broad spectrum fungicide like Subdue + Clearys 3336 will be mixed with a soluble phosphorous package, which is the fungicide used to sequester any root/stem disease. The soluble phosphorous is used to stimulate new roots. FYI: Drenches are best used as a preventative of problems. Once disease has set in, drenches are not as effective as a curative. This is often misunderstood and growers are unhappy with the results.

AIRBLAST VS. HAND SPRAY - Especially in larger nurseries, the airblast or blower sprayers have become popular. They are quite efficient in covering a large area in a short amount of time, and will also use less chemical per square area. They are best used for applying foliar nutritionals or a prophylactic layer of fungicide to the leaf surfaces. However for pests like mites, whitefly, mealybug and scale, airblast sprayers typically do not provide the necessary coverage. Here the hand gun method is more efficient. With a hand gun sprayer, the chemical can reach the undersides of the leaves, the stems and plant base. Both sprayers have their application in a nursery, but smaller nurseries will do just fine with the conventional hose reel, hand gun sprayer.

SAFETY FIRST - Many of the chemicals we are spraying are complex compounds designed to kill pests. Unfortunately that carries with it a hazard to the applicator as well as those in the vicinity of the spraying. Wearing a respirator, eye protection , rubber gloves and boots are imperative, and often the law, for good reason. The Tyvek disposable jump suits are also a nice addition to the safety of your applicator. In the Florida heat things like goggles or respirators are often taken off for comfort, but keep enforcing their use. REI’s are on the label to tell you when it is “safe to go back in the water”. Again, this is the law. Nutritionals are less hazardous, but can still cause respiratory, skin and eye issues. So here too, wear protective gear. 

HOW OFTEN SHOULD I SPRAY? - Not an easy question to answer. On average tree fields are sprayed monthly, and containerized trees every 2-3 weeks. Smaller woody crops are sprayed every 2 weeks, and foliage every week to 2 weeks. Scouting will help you spray just when it is needed, and obviously in wet summer months, some crops are getting a weekly rotation of fungicide. In drier months, mites may be more active, so it may help to go back and check the previous year’s spray records.

Miticides often need to be applied twice, back-to-back in a 5 day period as their life cycle is so short. After that, you might get by for several weeks before a reapplication. Stubborn diseases might need a weekly rotation, alternating chemistries. Spray programs are what Matt and I do best, so if you or your clients ever have questions, please call us. We provide this service to Harrell’s customers, as we want them to succeed. We really do work hard to provide our customers with the best service and products.