Did You Calibrate Your Sprayer? Here is An Easy Way to Do it


Dr. Erdal Ozkan

Pesticide Application Technology Specialist

Extension Agricultural Engineer

The Ohio State University


Have you calibrated your sprayer this year before the spraying season started? If yes, great! If not, there is still time to do that. You may ask: Why do I need to calibrate my sprayer? The answer is simple: If you don’t calibrate your sprayer, it’s as if you were driving your car with a speedometer that doesn’t work. You assume you know what speed you are traveling at from habit, but you are not really sure. The problem with a sprayer is that nozzles may be plugged or worn out, and application rates change with different field conditions which affect traveling speeds. Many growers don’t take these factors into account.

Applying pesticides at the proper rate is essential to achieving satisfactory weed, disease, and insect control. The directions on the container label tell what application rates give the best results. However, proper application rates will be attained only if sprayers work well and are calibrated correctly.

Calibrating a boom sprayer is not as difficult as it sounds. It usually doesn’t take more than 30 minutes, and only three things are needed: a watch (or smart phone) showing seconds, a measuring tape and a jar those measures in ounces. The ultimate goal is to calculate the actual rate of application in gallons per acre to check for accuracy, or make adjustments as needed

Here is an easy method to calibrate a boom sprayer:

There are several ways to determine the actual application rate, but the one outlined below is perhaps the easiest, and do not require difficult calculations:

  1. Fill the sprayer tank with water.
  2. Run the sprayer, inspect it for leaks, and make sure all vital parts function properly.
  3. Measure the distance in inches between the nozzles. Then measure an appropriate distance in the field based on this nozzle spacing. A table available at http://ohioline.osu.edu/factsheet/fabe-520 shows various nozzle and row spacings and the distance you must travel. For example, the travel distance for a 15-inch nozzle or row spacing is 272 feet, for 20-inch nozzle or row spacing is 204 feet; for a 30-inch nozzle or row spacing, the distance is 136 feet.
  4. Drive through the measured distance in the field at your normal spraying speed, and record the travel time in seconds. Repeat this procedure and average the two measurements.
  5. With the sprayer parked, run the sprayer at the same pressure level and catch the output from each nozzle in a measuring jar for the travel time required in step 4.
  6. Calculate the average nozzle output by adding the individual outputs and then dividing by the number of nozzles tested. If an individual sample collected is more than 10 percent lower than the flow rate of the same nozzle when new (check the nozzle catalogs or web site) check for clogs and clean the tip. If this does not help, then you should replace the nozzle. If an individual sample collected is more than 10 percent higher than the flow rate of the same nozzle when new, this indicates the nozzle orifice is worn out. In this case, replacement of the nozzle is needed.
  7. Repeat steps 5 and 6 until the variation in discharge rate for all nozzles is within 10 percent of the nozzles when they were new.
  8. The final average output in ounces you get is equal to the application rate in gallons per acre.
  9. Make adjustments if necessary. Compare the actual application rate determined above resulting from the calibration process with the intended application rate.  If the difference between the calculated actual rate and the intended rate is more than 5% of the desired rate, you need to make adjustments to bring the error below 5%. You can start by changing the pressure. Lowering the spray pressure will reduce the spray delivered; higher pressure means more spray delivered.  Do not exceed the pressure rate recommended for the nozzles when adjusting the pressure rate. Remember that changes in pressure will result in changes in droplet size. So, don’t go to extreme pressure settings just to reach the desired output from nozzles. You can also correct the application error by changing the travel speed.  Slower speeds mean more spray delivered, faster speeds mean less spray delivered.  If changes in either pressure or travel speed, or both do not bring the application rate to the desired rate, then you may have to select a new set of nozzles with smaller or larger orifices. Learn how to make these adjustments and additional information about calibration at http://ohioline.osu.edu/factsheet/fabe-520
  10. Recalibrate the sprayer often. Calibrating a sprayer once a year is not enough.  It should be calibrated several times throughout the season to compensate for wear in pumps, nozzles, and metering system; and when spraying in a different farm than the one where the previous calibration was made. Changes in the soil surface characteristics and topography cause changes in travel speed which will directly affect the application rate.

In summary, properly maintained spraying equipment is critical to pest control and user safety.  A properly calibrated sprayer saves you thousands of dollars in chemical cost; improves yield; reduces the chance of damage to your crop as a result of over application and potential risk of contamination of the environment with pesticides. Safety is extremely important.  Use water instead of chemical mixtures when calibrating your sprayer, and wear gloves and protective clothing.


Early Season Cucurbit Pests

Growers are ramping up to plant pumpkin, squash, melon and cucumbers through May and into June. Here are some key pests to keep in mind with seedlings and small plants this time of year.

Striped cucumber beetle – This small black and yellow striped beetle is a major pest of all cucurbits early season. In addition to the heavy feeding damage that can be inflicted upon seedlings, this feeding injury can also transmit bacterial wilt to the plant which will stunt or kill the plant. Growers can control this pest in several ways such as buying FarMore FI400 treated seed, which contains several fungicides paired with thiamethoxam insecticide that provides seedling protection for 2-3 weeks after emergence. Using an in-furrow treatment of a systemic insecticide at planting will provide a longer window of control, between 4-6 weeks. Another management option is to scout for beetles on emerged seedlings, and based on seedling stage, use a foliar spray when the threshold is exceeded according to the guide below:

0.5 beetles per plant for cotyledon through 1st leaf

1 beetle per plant for 2nd and 3rd leaf

2 beetles per plant for anything after the 4th leaf stage

Striped cucumber beetle adult.

Regardless of method of treatment, be sure to scout for these beetles and their damage on the underside of the cotyledons and early leaves every few days as severe damage can occur rapidly in a short period of time. Pollinators can also be affected by systemic insecticides present in pollen and nectar, so seed treatments to some degree and in-furrow products should be considered before use. Foliar applications of insecticides should be made in the evening to minimize pollinator impact.

Squash Vine Borer – The damaging stage of this pest is actually a caterpillar from moth that mimics a wasp which becomes active in early June. The best management practice for this pest is to put up a pheromone trap next to the field and monitor the number of moths caught. A week after adult moths are caught in the trap, usually around mid to late June, apply an insecticide targeted at the base of the plants where the eggs are laid 7-10 days apart for up to four weeks. If the caterpillar bores into the stem of the plant, treatment will not be effective. Systemic products such as imidacloprid, used either as a seed treatment or in-furrow application at planting, will not control this pest.

Squash vine borer moth.


Squash vine borer larva.

Squash Bugs – These true bugs overwinter as adults in nearby fields and can attack seedling and smaller plants with sucking mouth parts that can collapse leaves and stems. These pests can also vector yellow vine decline, a bacterial pathogen that can cause stunting and death in seedling plants. Plants infected with YVD will turn yellow about a month after being infected, and there is no remedy. YVD can look very similar to injury caused by tunneling squash vine borer larvae, so if a plant is suspected of YVD, check the base for evidence of SVB larva, usually spotted by frass surrounding entry hole. If more than one egg mass per plant is found, treatment is warranted once the nymphs hatch. If nymphs mature to adults, they are harder to control.


Squash bug eggs

Squash bug adult.

Yellow vine decline infected plant.


A list of recommended insecticides for all these pests can be found in the 2017 Midwest Vegetable Production Guide (https://btny.purdue.edu/Pubs/ID/ID-56/).

Graft, Roll, Crimp, Crush, and Strip: A Few of the Steps included in an Ongoing Study

Every production technology or technique has pros and cons. Occasionally, using two techniques or technologies simultaneously may offset their individual disadvantages and make it easier to use both. This is one idea behind our evaluating the combined use of reduced tillage and grafted vegetable plants. While both have clear benefits, their counterparts (conventional tillage featuring highly worked, often pulverized soil and standard single-variety transplants) are standard. Cost, timing, familiarity, and other obstacles have limited the use of reduced tillage and grafted plants.

In 2016, we completed an experiment in Wooster comparing the performance of grafted and standard tomato transplants in no-till and strip-till plots established in wheat seeded in Fall-2015. We reported three results in VegNet, at the OPGMA Growers Congress, and in a report to the OVSFRDP: 1) yields were higher in strip-till plots than in no-till ones, 2) grafted plants out-yielded ungrafted ones in both tillage systems, and 3) yield was greatest in strip-till plots containing grafted plants. We are repeating the experiment in 2017 to see if those trends hold under other conditions. Plants representing three rootstock-scion combinations were grafted three weeks ago and the ‘Hopewell’ wheat was rolled/crimped/crushed on May 17. Weather-permitting, on May 22, a PTO-driven rototiller will be used to create ten-inch wide strips of soil tilled to six inches deep in some areas and herbicide will be applied in a two-foot wide band centered on each strip. They and the no-till plots will be transplanted on May 23.

Rye, rye/vetch mixes, and other crops are better than wheat for no-till/reduced-till (including strip) vegetable production. We are using wheat partly because it may be one crop that growers can experiment with easily since it is abundant. We have used a PTO-driven rototiller (with outer tines removed) for a similar reason. True strip-till units are currently above our budget. Therefore, like growers, we experiment with equipment on hand. The goal has been to describe what happens when ‘alternative’ approaches are used and to improve our use of them. Input from growers continues to be very helpful in the process. Overall, given the documented benefits and challenges associated with using grafted plants and reduced-till approaches, using them together may be particularly useful. Look for updates on the study, stop by to visit, or contact Matt Kleinhenz (kleinhenz.1@osu.edu) or Zheng Wang (wang.2735@osu.edu) for more information. The pictures below show the roller/crimper at work and the condition of the wheat at and after the process. Paper clips on wheat stems show locations of damage due to rolling/crimping.

Managing Phytophthora Blight in Peppers

Phytophthora blight has become a very serious problem in peppers and cucurbits, particularly in areas with concentrated vegetable production.  The pathogen is a water mold that thrives under conditions of high moisture and high temperature. It produces motile spores (zoospores) that are attracted to plants, then form a structure that allows them to infect, and aggressively attack any type of plant tissue. Zoospores can be splashed onto leaves, stems and fruits during rain events and overhead irrigation. Phytophthora blight is often seen first in low spots or other poorly drained areas of production fields, but the disease also occurs on well-drained, even sandy soils if the environmental conditions are right.  An increase in intensive rainfall events that result in soil saturation and standing water in fields in the last decade or so is certainly a contributing factor to the uptick in problems with Phytophthora blight.

Effective management of Phytophthora blight in peppers requires an integrated approach:

Crop rotation.  Phytophthora produces structures called oospores that can survive for a number of years in the soil.  Plan to rotate out of peppers, cucurbits or green beans for 4-5 years if Phytophthora blight has been a problem.

Resistant varieties.  A few pepper varieties are resistant to the root rot phase of the disease.  In general, these varieties are susceptible to the crown rot phase, which affects foliage and fruits. Varieties with moderate to good resistance to Phytophthora blight are: Paladin, Aristotle, Declaration, Intruder, Vanguard (bell); Hechicero (jalapeño); and Sequioa (ancho).

Well-drained soil. Avoiding standing water is critical to limiting the movement of Phytophthora from plant to plant.

Avoid surface water for irrigation. We have found Phytophthora in irrigation ditches and ponds as early as late June in vegetable production-intensive areas in Ohio.  Using surface water for irrigation is risky, especially if Phytophthora is present in fields near surface water sources.

Plant on raised beds. Prepared properly, raised beds will help prevent standing water near pepper plants.  If possible beds should be domed, and there should be no depressions in the soil surrounding the plants.

Sanitation.  Phytophthora can be moved from an infested field to a clean one on soil clinging to boots, equipment, etc.  Power washing to remove soil is a good first step, followed by rinsing with a sanitizer.

Fungicides.  There are a number of fungicides labeled for use on peppers to manage Phytophthora blight  (see table below).  The newest product, Orondis, has very good efficacy against this disease.  It is available in the Midwest this year as a co-pack with either Revus (Orondis Ultra), Ridomil (Orondis Gold) or Bravo (Orondis Opti).  Pre-mixes will be available in 2018. There are many restrictions on the use of Orondis – including the number of applications (no more than 1/3 of total applications for Phytophthora blight) and when it can be applied (to the soil or to the foliage but not both).  Orondis Ultra and Orondis Gold can be applied in transplant water or through the drip, although Orondis does not move much in soil and emitters need to be right next to the plant.  If the pepper variety is susceptible to Phytophthora blight, it may be a good idea to apply Orondis Gold or Orondis Ultra at planting, and follow up later with a program containing at least two of the fungicides with activity against Phytophthora (see table).  Research conducted at the University of Illinois has shown that adding a copper-based fungicide to these foliar applications can improve their efficacy.  If the pepper variety is resistant to Phytophthora, any of the three Orondis products can be used in a foliar fungicide program that includes other effective fungicides.  The Bravo component of Orondis Opti will not help with Phytophthora blight, but will control anthracnose.  Orondis Gold is considerably more expensive than Orondis Ultra and Orondis Opti, and resistance in Phytophthora to the Ridomil component of Orondis Gold has been found in numerous locations.

Larger, Better, and More Stress-tolerant Crops with Microbial Biostimulants?

An increasing number of growers use an ever-larger number of microbe-containing biostimulants to jump-start crops and/or to increase their yield or quality. Also, some claim that using these products makes all that possible with lower inputs, including fertilizer. We (https://u.osu.edu/vegprolab/) are coordinating a  USDA NIFA-, SARE-, and industry-sponsored effort to help vegetable growers select, use, and evaluate the effectiveness of these biostimulants more reliably. One experiment underway at the OARDC in Wooster includes multiple commercial inoculants applied to leafy vegetables and carrot grown in high tunnels. A second set of experiments this summer will include inoculants applied to field-grown fresh market tomato and butternut squash. A third set of experiments will be completed on farms in Ohio and five other states. Use https://u.osu.edu/vegprolab/research-areas/vegebiostimsferts/ and later issues of VegNet to learn more about this work. Images below are from the carrot study seeded in late March in which root and shoot characteristics are being monitored. Plots will be harvested soon. For more information, please contact Matt Kleinhenz.1@osu.edu and Zheng Wang.2735@osu.edu.


What Are the Most Worrisome Diseases in Your Vegetable Crops?

Many specialty crop growers are aware of the USDA IR-4 Minor Use Program, which works to promote registration of products for  pest, disease and weed management in “minor use” crops – including vegetables, fruits, herbs and spices, among others.  The US IR-4 Program will participate in a Global Minor Use Summit in Canada later this year, and is asking for help in identifying the most important priorities among growers worldwide.  This is a good opportunity to voice your opinion about the diseases, pests and weeds that are your greatest concern and for which labeled products are needed to manage the disease.  In some cases this is a matter of expanding labels that include other crops, while in others it may involve research to find a solution to a problem.

For example, bacterial diseases such as bacterial spot and bacterial canker in tomatoes, are very difficult to manage in the field, and therefore can cause significant losses.  There are no highly effective products available, so research is needed.  

Please take the time in the next ten days to let us know what you think are the most important crop/disease, pest or weed priorities on your farm or community.  Which are the ones that keep you awake at night? You can send me an email at miller.769@osu.edu or reply in the Comment section below.

Use of compost products as raised bed growing media

A project started in Hocking County in fall of 2016 was the creation of an Urban Farm at the food bank that serves the ten county southeast Ohio Appalachian region.  This will allow the food bank to achieve its own personal stream of fresh produce for use in sales, Senior Farmer’s Market vouchers, Meals on Wheels as well as the USDA Summer Nutrition program for school children.

Seven raised beds were constructed with a  fill need of approximately 8 cubic yards of material.  Funding would not allow purchased topsoil so alternatives were sourced locally.  One local partner in The Urban Farm at Southeast Ohio Regional Kitchen is Athens Hocking Recycling Center LLC.  Their Organics product is made by combining local food waste obtained through a subscription pick up process which is mixed with wood chips in large windrows via hot composting.  The finished product is screened and sold by the yard for bulk pick up.  AHRC has been a partner for local food production programs and was able to provide 4 yards of finished compost at cost.

The second compost product is produced in Hocking county.  The City of Logan collects municipal yard waste which is cold composted in large piles on site at the city maintenance facility.  This product had been used in spring of 2016 as the sole growing medium in raised beds at The Children’s Educational Garden at the Hocking County fairgrounds and plants exhibited extreme chlorosis symptoms.  Half of the raised beds would contain AHRC compost, the other half City of Logan.  This would allow for comparison for selection of future media as expansion of the garden progresses.

The first compost evaluated was AHRC Organics.

Here is a close up of the product, some cover crop seeds are visible:


Soil test results for AHRC Organics:


Pretty impressive numbers.  High organic content,  lots of nutrients.  You can still see some wood pieces as well as some egg shells if you look close.  It is an excellent soil amendment  The problem with using it straight is the alkaline pH of 7.7 can cause some problems with certain nutrients being available right away.   The soil test states to add sulfur to combat that.

Next up is municipal yard waste from the City of Logan.


Not bad looking stuff,  still some bits and pieces.  This sample was cold composted for 3-4 years in place prior to being delivered.The soil test results:


Very similar numbers noted here.  High organic matter,  lots of nutrients,  same alkaline pH.  I did the same with both.   Added ammonium sulfate fertilizer then sowed cover crop seed.


Ammonium sulfate has  both sufur, to correct the pH and some nitrogen to help both the cover crops grow and help the soil bacteria break down the residual carbon bits.  My hope is that the fertilizer, the cover crops and the winter will combine to help both of these growing media get to a good point for vegetables by 2017.  Anecdotally when doing research what I encountered regarding wood/leaf compost seemed to suggest little fertility and an acid finished product. More to be used as a soil amendment and not a pure growing medium.  Soil testing suggested the opposite.  Both growing media will be reevaluated in spring 2017 after first spring vegetable harvest, then later in summer harvest for production, weed pressure,  and chlorosis symptoms.

Brown Marmorated Stink Bugs Already Active

It’s that time of year when many pests become active and begin moving from their overwintering sites to crop fields. One of the pests we have been monitoring statewide over the past six years is the Brown Marmorated Stink Bug (BMSB). This is a rather large brown mottled stink bug known to attack field crops, landscape and ornamental plants, and a wide array of fruit and vegetable crops including apples, peaches, caneberries, blueberries, grapes, beans, sweet corn, peppers, tomatoes, and many more crops.

Brown marmorated stink bug, adult female; note the distinctive white bands on the antennae.

Brown marmorated stink bug, nymphs, feeding through husks of sweet corn.

In our pheromone trapping program in Ohio since 2011, we have typically geared up for trapping this pest in early June and finished in September, but as part of a large multi-state research project this year, we established monitoring sites by early April in several central and southwest counties using two different style traps; the traditional black pyramid and a new clear panel sticky trap. Both traps use a dual pheromone lure that is quite attractive to both male and female adults as well as to nymphs of BMSB. The study is designed to compare one type of trap to the other in terms of catch efficiency, and to determine when the BMSB become active and leave their overwintering locations in nearby woods to move into adjacent fields. So far we’ve been catching male and female BMSB in Franklin, Greene, and Clinton counties since mid April.


New clear sticky panel trap for BMSB.

Traditional pyramid style BMSB trap.

Even though we haven’t seen much injury from BMSB in fruit and vegetable crops in most Ohio locations over the past few years, it is possible that the overwintering survival rate of the stink bugs is higher this year due to the mild winter.  It would be prudent for growers to keep a close eye out for this particular pest in 2017. For more information about the biology and management of this pest, visit http://www.stopbmsb.org.