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April 15
Preparing for Freezing Temperatures in the Tomato High Tunnel

​The low tonight is forecasted to be 28 F.  In preparation, we placed clear plastic over each row.  This type of plastic is not vented.  Therefore, one must be very careful to watch the temperature inside the tunnel when there is direct sunlight.  Although we made it through last night, tomorrow morning will be the real test!  UPDATE:  After the cold night of Tueday morning--the tomatoes made it through fine.  However, it didn't get as cold as predicted.  We found it difficult to manage the low tunnels when the sun was out during the day.  Growers should be very careful about clear plastic tunnels without vents.  The tunnels can get very hot.  

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Clear plastic low tunnels over the tomatoes in the high tunnel.  Note that there are no vents.  Care must be taken to vent low tunnels if necessary.  This can be done by opening the ends.  The ends would then be closed again well before nightfall.  


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The next morning, condensation can be seen inside the low tunnels. This indicates that the temperature inside the low tunnel is higher than outside the low tunnel.  The temperature reading at 7 a.m. inside the low tunnel was 42 F, outside the low tunnel (inside the high tunnel) it was 35F.  The temperature at 9 a.m. was 73 F inside the low tunnel, outside the low tunnel 58F.  




April 12
Claybacked Cutworm on Tomato

At the Southwest Purdue Agricultural Center we have three high tunnels.  Two of them have tomatoes plants, the third has pepper plants.  All of the plants were transplanted into the high tunnels this past week.  As I see pests in the greenhouses, I will try to report them here.

 

 A few days ago, I found claybacked cutworm on tomato plants.  On Wednesday, one of the plants was cut off at soil level.  It appeared to be cutworm damage, but we could not find the pest.  We replaced the tomato plant.  The next morning in the early dawn, I went into the hightunnel and found the replacement tomato plant eaten in the same manner.  Using the flashlight application on my phone I was able to find the cutworm right beside the damaged tomato plant. See photos below.

 It is important to note that the cutworm, identified by John Obermeyer in the Purdue University Entmology Department, is a claybacked cutworm, not a black cutworm.  Black cutworms do not overwinter in Indiana and would not be expected this time of year.  Claybacked cutworms do over winter as mature larvae.  See this link for more information on cutworms. See the Midwest Vegetable Production Guide forCommercial Growers 2014​ for management help. 

 It is also important to note that I was able to find the cutworm at first dawn.  This insect is nocturnal.   So, the lesson is that in order to find cutworms, one must scout at first dawn.  In other words, the early bird gets the worm!

 I am not an entomologist, but if you have questions about this important pest, please let me know and I will try to get answers for you. 

 

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Claybacked cutworm damage on tomato.  I found the cutworm at dawn, when it was too dark to take a photos and placed the larvae back on the plant to take photoos when it was light.  

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Photo of the claybacked cutworm that had been eating the tomato transplant.  

April 08
Fungicide Updates-April 2014

Midwest Vegetable Production Guide Update-Hard copies of the Midwest Vegetable Production Guide for Commercial Growers 2014​ have been available since early January.  However, this guide, also known as the ID-56, is also available for as an on-line version.  One advantage of the online version is that it is free versus the $10 price for the hard copy.  Another advantage of the on-line version is that updates can be added when needed.  Updates and changes that have been made since the printing of the ID-56 are listed below:

Fruiting vegetable chapter-The rate for Fontelis on tomato for Botrytis gray mold and for early blight/Septoria leaf blight was changed to 16-24 fl oz./A on page 123.  

Fruiting vegetable chapter-The fungicide Priaxor was added for anthracnose, Botrytis gray mold (suppression only), early blight and Septoira leaf blight, late blight (suppression only) and white mold.  The rate for all the diseases above is 4-8 fl. oz./A except for late blight, which is 8 fl. oz./a.  Note that Priaxor is the only foliar fungicide listed for tomatoes and white mold.  However, Priaxor is not labeled for the greenhouse.  Applicators must be in possession of the supplemental label. 

Cucurbit chapter-In the watermelon variety resistance to Fusarium wilt table on page 97, the watermelon variety Distinction now has a rating of ‘++++’, meaning it has an excellent Fusarium wilt resistance rating. 

Cucurbit chapter-Proline 480 SC is now labeled for Fusarium wilt of watermelon at 5.7 fl. oz. per acre.  May be applied by ground or chemigation application equipment.  Do not use in water used for hand transplanting. 

This product has been labeled as a result of research performed at Purdue University and elsewhere.  The Proline label allows one drip application.  If Proline is used as a drip application for Fusarium wilt, use it at transplant.  I have been able to show that Proline can lessen the severity of Fusarium wilt of watermelon.  However, the results depend on many factors including the amount of the Fusarium wilt fungus in the soil and the host resistance of the variety used.  If you have any questions or thoughts about using this product for Fusarium wilt of watermelon, please contact me at the phone number or email to the right. 

Cucurbit chapter-The fungicide Merivon was added to several diseases in the chapter at 5.5 fl. oz./A:  anthracnose, gummy stem blight, powdery mildew and Plectosporium blight.   Alternaria leaf blight was added at 4-5.5 fl. oz./A.  Applicators must be in possession of the supplemental label. 

I had the opportunity to use this product on powdery mildew of cantaloupe a few years ago:  I had excellent results.  However, Merivon has active ingredients in groups 7 and 11.  My research has shown that in the past, group 7 active ingredients work well on powdery mildew (for example, Pristine and Fontelis).  Group 11 products have not worked well for powdery mildew of cucurbits in Indiana. 

Sweet corn chapter-The fungicide Priaxor was added for use on several diseases-page 188.

Onion chapter-The fungicide Merivon was added for use for Alternaria purple blotch, Botrytis leaf blight and downy mildew.  Page 161. 

Legume chapter- The fungicide Priaxor was added for use on several diseases.  Pages 146-147.

If you are unable to access the on-line version of the Midwest Vegetable Production Guide for Commercial Growers 2014 or have any questions, please contact me.  Or feel free to comment below.​

March 28
Ethylene Damage on Tomato Transplants

I received a call from a greenhouse grower recently with a tomato transplant problem.  The grower described yellow seed leaves and curled foliage. The grower was able send a couple excellent photos (Figure 1).  There were a few clues that the symptoms might be due to a heater problem. In Figure 1, some of the seedlings have leaves that are curled down and stems that are twisted (epinasty in botanical terms). Epinasty is a common symptom of ethylene damage. Ethylene is a common by-product of incomplete combustion of several different types of fuel.  Incomplete combustion is often the result of heaters that are not working efficiently.  Tomatoes are very sensitive to ethylene damage.

A second clue is to take a closer look at the yellow seed leaves (Figure 1). Ethylene damage does not include yellowing.  Furthermore, there is a spotting on the lower leaves that is not typical ethylene damage.  I believe that the symptoms on seed leaves were as a result of a different compound, perhaps sulfur, a heavier than air compound that would remain relatively close to the heater. The grower confirmed that the yellowing leaves were close to the heater, while the curling leaves, caused by ethylene gas, were spread throughout the greenhouse.

While some greenhouses are heated with a furnace attached to the greenhouse, many greenhouses are heated with a standalone unit inside the structure. In the example above, the grower stated that the heater was of this latter type-a standalone unvented unit. While this type of heating is not recommended, natural gas, propane and kerosene generally burn clean and do not need to be vented. However, even units that burn clean fuels may cause problems if out of adjustment (see citation below). 

I cannot prove that the symptoms in Figures 1 above are caused by ethylene.  But a few years ago, we witnessed ethylene-like damage at a greenhouse here at the Southwest Purdue Agriculture Center (See article in the November 2007 Vegetable Crops Hotline. Therefore, we were able to confirm that ethylene was the cause of the symptoms shown in Figure 2. Given the similarities of the two examples and the circumstantial evidence, I believe the example given in Figure 1 was due to a heater malfunction. The grower reports that after the heater was serviced, the plants began to look healthier. 

Poorly adjusted heaters can also add water to the greenhouse air-as much as 22 gallons of water a night!  This unwanted moisture can lead to disease problems. 

      To avoid damage from ethylene and other air pollutants:

1. Have unit heaters checked by a professional and follow maintenance recommendations.

2. Assure adequate air supply for complete combustion. For each 2500 BTU’s of heater output, 1 sq. in. of vent cross section is needed.

3. Prevent back drafts. Make sure the chimney extends 2 ft. above the ridge of the greenhouse, or 2 ft. above a 10-ft. line to any part of the structure.

4. Install an inexpensive carbon monoxide detector. If carbon monoxide levels rise it’s likely ethylene and other pollutants are present also. And if carbon monoxide levels are high it is a significant human health hazard.

5.  Scout for possible growth effects of ethylene and investigate right away if you see anything.

 

Additional Resources: Bartok, J.W. Problems With Using Unvented Greenhouse Heaters

 

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Figure 1:  The tomato seedlings above exhibit downward curled leaves (red arrows) which maybe a symptom of ethylene  

damage and yellow seed leaves with lesions (red circles), a possible symptoms of sulfur damage (Contributed Photo).  

PICT0008 copy.JPG         Figure 2: These tomato plants are exhibiting epinasty or a downward growth of the leaves in response to ethylene produced from a malfunctioning heater in a greenhouse. The topmost leaves are growing normally because the plants were removed to a separate greenhouse after exposure to ethylene. (Photo by Dan Egel).

March 16
Calibration of hand sprayers

In my last blog, I discussed the relative advantages and disadvantages of different types of pesticide sprayers that are powered by humans.  That is, a hand sprayer is any sprayer that depends on humans to move the sprayer from plant to plant.  This is in contrast to pesticide sprayers that are moved along a field by a tractor. 

In a tractor borne sprayer, it is possible to set a constant speed and pressure.  This fact facilitates calibration.  In the space below, I would like to discuss one method whereby it might be possible to calibrate a hand sprayer.  

As stated in my last blog, make sure that the product is labeled for the host and disease(s) that are of concern.  If the area to be sprayed is a greenhouse, make sure the product can legally be applied to a greenhouse (or high tunnel).  In this example, the fungicide to be applied has a label that requires 1 lb/acre of tomatoes.  

In our example, we will be applying the fungicide to a greenhouse.  The greenhouse is 30 ft x 90 ft.  The total number of square feet in the greenhouse is 2700.  2700 sq. ft. per greenhouse divided by 43560 sq. ft per acre = 0.062 acres/greenhouse.  That is, our greenhouse is 0.062 acres.  Since we know our product is applied at a rate of 1 lb/acre, then we know that we must apply 0.062 lbs of product to our greenhouse.  To make it a bit easier, we will use ounces.  If a pound equals 16 oz., 0.062 lbs of product equals very close to 1 oz. 

But how much water is needed to apply 1 oz. of our fungicide to the greenhouse tomatoes?  Remember that the greenhouse is 0.062 acres.  We need to know how much water will be needed to cover 0.062 acres of greenhouse tomatoes. 

To determine how much water to apply to our greenhouse of tomatoes, apply water to a portion of the greenhouse and then calculate how much water it will take to apply a spray to the entire greenhouse. 

In this greenhouse example, there are 6 rows of tomatoes each 90 feet long on 5 foot centers.  If we apply water to one row of tomatoes, we will be able to determine how much water to apply to the entire greenhouse.  We place 5 gallons of water in our back pack sprayer and apply it to our tomatoes as if we were actually applying fungicide.  Use a slow and steady motion.  Carefully apply water to each plant.  Avoid stopping in the middle of the row and have the person who will do the applications be the same person to conduct this sprayer calibration.  

After we have applied water to one row, we will measure the contents of the sprayer.  We find out that we have 4.5 gallons left in the sprayer.  That means that we applied 0.5 gallons to one row.  Since there are 6 rows, 3 gallons of water will be needed to cover the entire greenhouse. 

Place the amount of product calculated above for the greenhouse, 1 oz. of fungicide, in 3 gallons of water. 

There are other ways to calibrate a hand sprayer.  For example, if you know accurately how much time it takes to apply fungicide to one row of tomatoes (or to the entire greenhouse), one could measure how much water the sprayer puts out in a minute and thus calculate the total amount of water. 

Perhaps the most important factor is consistency.  Follow a steady motion across all the plants.  Use a constant pressure.  Nozzle wear will affect calibration as will new nozzles.  Recalibrate the sprayer if someone else will do the spraying. 

If you have questions or concerns, please let me know. Or maybe you would like to share an idea in the comments below. ​ 

February 12
Application of Fungicides by Hand Sprayer

Occasionally it becomes necessary to apply fungicides to an area too small for treatment with a tractor-mounted sprayer.  Below, I share my thoughts on examples of equipment that might be used to treat small areas. 

Let’s consider an example where one wants to apply a fungicide for management of Botrytis gray mold on tomatoes in a greenhouse.  First, make sure that the product is labeled for tomatoes, gray mold and the greenhouse.  (Some labels have statements that prohibit pesticide applications in a greenhouse.  In other cases, the label is silent on the matter of greenhouse applications.  In the latter case, greenhouse applications may be made-with care!  See page 40 of the 2014 version of the Midwest Vegetable Production Guide for Commercial Growers <mwveguide.org> for more information. )  Make sure to read all the label statements for precautions such as worker protection clothing, Re-Entry Interval (REI) and Pre-Harvest Interval (PHI). 

What type of sprayer should one use?  Let’s review a few different types of sprayers.

1. The hand sprayer-This is the type of sprayer that one would buy at the local garden center or hardware store (Figure 1).  Most have a capacity of 1-2 gallons.  I like the hand sprayers that have a quick release valve on the side.  After the application is complete, this valve can be used to release pressure prior to opening up the tank.  The release of pressure makes it less likely that pesticide will escape out of the tank when the pump handle is unscrewed.

 
   Figure 1: The common hand sprayer may be purchased at the
   local hardware or garden store. Note that this one has a quick
   release valve.

This type of hand sprayer is readily available, inexpensive and easy to use.  However, using a hand sprayer to apply fungicide to a row of tomatoes, for example, can be difficult.  Applications with a hand sprayer are often made with an up and down motion while moving down the row of plants.  It can be difficult to apply the same amount of spray to every plant in this fashion.  In addition, the nozzle of most hand sprayers is adjustable from a thin stream to a wide spray.  The wide spray is more useful to fungicide applications; however adjustment of the nozzle may be inadvertently altered, thus changing how the spray is applied. 


2. Backpack sprayers may be ordered through catalogues or on-line (Figure 2).  Many backpack sprayers may be pumped up by hand while applications are being made.  Sprayers with a pressure gauge on the handle make it easier to apply fungicide with a consistent pressure/amount to each plant.  Some backpack sprayers have a flat fan or hollow cone nozzle.  These types of nozzles are made for fungicide/pesticide applications, unlike the adjustable nozzles described above which are multi-purpose (Figure 3).

 
   Figure 2:  This backpack sprayer has a pressure gauge on
   the wand and a separate pump handle so that pressure can
   be maintained while spraying.
 
 

   Figure 3:   The top nozzle is a flat fan nozzle designed
   for pesticide applications.  The bottom multi-purpose
   nozzle may be adjusted from a thin stream to a wide spray
   and may be changed inadvertently during a pesticide
   application.
 
3. CO2 sprayers can be purchased that are worn as a backpack (Figure 4).  Instead of pumping up these sprayers by hand, a CO2 cylinder is used to propel the spray.  This allows for a more consistent spray.  Typically, these sprayers utilize a boom sprayer with hollow cone or flat fan nozzles.  Using a boom with 3 or 4 hollow cone or flat fan nozzles makes it much easier to apply fungicide consistently to a large section of plants compared to applying the same product with a wand. 


   Figure 4:  Here the use of a backpack CO2 sprayer
   is demonstrated.  Advantages of this sprayer are
   the CO2 propellant that allows a consistent spray
   and a boom of 4 nozzles that makes applications
   easier and more effective.
 
4. Growers may want to devise a system of their own.  Here I describe a piece of equipment that Dennis Nowaskie, superintendent of the Southwest Purdue Agricultural Center, created to apply fungicides to tomatoes in our high tunnels (Figure 5).  The sprayer consists of a tank and pump which was manufactured to be used on the back of an ATV.  The tank is mounted to a flat piece of aluminum which is mounted on wheels so that the entire unit may be pulled-sort of like a wagon.  The pump is powered by a 12 volt battery which has a small trickle charger attached in order to charge the battery when not in use.  Two booms are attached vertically on either side of the pump.  Either boom or individual nozzles can be turned on and off to spray the crop on either side or any height.  Either boom can be lowered so that crops close to the greenhouse wall can be sprayed.  The sprayer is pulled at a consistent speed between the rows. 


   Figure 5:  This greenhouse sprayer, designed by
   Dennis Nowaskie at the Southwest Purdue Ag Center,
   can be pulled between the rows of tomatoes.  Each
   nozzle may be turned off and on and both booms can
   be lowered if necessary.  This sprayer is an example
   of the type of  equipment that can be fabricated to
   apply fungicides to a small area.
 
Choosing the right piece of equipment is just a part of the battle.  Next, the sprayer needs to be calibrated.  While most growers understand how to calibrate a tractor mounted sprayer, it may not be obvious how to calibrate a sprayer that is powered by a human.  In my next blog, I will describe one way in which hand sprayers of the sort described here can be calibrated to deliver the right amount of fungicide to the plant.

 

November 13
2014 edition of the Midwest Vegetable Production Guide for Commercial Growers

The annual update of the Midwest Vegetable Production Guide has been sent to the printer and will be ready in plenty of time for distribution at winter meetings.  In addition to the purchase of a hard copy of the Guide for $10, the Guide is available free on-line at mwveguide.org.  The on-line version is updated whenever changes are made throughout the year.

Every year, the ID-56, as the Guide is known in Indiana, has recommendations for fertility, varieties and pest control for crops from asparagus to zucchini.  You may have a Guide from a previous year, but I urge you to purchase or download a new one since the guide changes every year.  Below, I have listed a taste of the larger changes that are listed in the Guide for 2014.  

Disease Management

The watermelon variety resistance to Fusarium wilt table has been updated with new varieties — see Cucurbit Crops chapter.

• A new table (pollenizer watermelon resistance to anthracnose) was added to the Cucurbit Crops chapter.

• Luna Privilege® has been labeled for several diseases of watermelon — see Cucurbit Crops chapter.

Weed Management

Prowl H2O® is now labeled for use between rows of melons (see the Cucurbit Crops chapter) and green onions (see the Dry Bulb and Green Bunching Onion, Garlic, and Leek chapter).

• Dual Magnum® was added for several crops.

• Anthem® and Anthem ATZ® are now labeled for preemergence and postemergence weed control in sweet corn. Both herbicides provide preemergence control of many grass and broadleaf weeds and postemergence control of many broadleaves. Anthem®

is a mixture of pyroxasulfone (Zidua®) and fluthiacet (Cadet®). Anthem ATZ® is a mixture of atrazine,

pyroxasulfone (Zidua®), and fluthiacet (Cadet®). These herbicides have an 18-month replant restriction for all other crops except corn.

Insect Management

Closer® was added to the recommendations for control of aphids, whiteflies, and plant bugs on several crop groups.

• Blackhawk® was added to the recommendations for control of caterpillars and Colorado potato beetles on several crop groups.

• The threat from the invasive brown marmorated stink bug was specifically addressed for several crop groups.

 

For your copy of the Guide, go to one of the winter meetings in 2014, ask your County Educator or point your browser to mwveguide.org.  For more information, call Dan Egel and (812) 8860198 or email egel@purdue.edu.

 

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 About this blog

 
About this blog 

Dan Egel is an extension plant pathologist with Purdue University who works with vegetable growers across the state of Indiana. This blog will highlight recent diseases issues, management options, meeting dates and new publications relevant to vegetable growers. Dan is located just north of Vincennes at the Southwest Purdue Agricultural Center.

 

Contact Information

Dan Egel
Southwest Purdue Agricultural Program
4369 N. Purdue Road
Vincennes, IN 47591
Phone: 812-886-0198

 www.watermelondr.info