Upcoming Produce Safety Training (November 6-7, 2017)

The Vermont Agency of Agriculture and UVM Extension are co-sponsoring a VT-Style Produce Safety Alliance (PSA) Grower Training on Tue-Wed, November 7 & 8, 2017 (8:30am – 5:00pm) at the VYCC Monitor Barn in Richmond, VT. This is the official required training for FSMA covered farms (Click here to determine whether your farm may be covered or exempt).


The $30 heavily subsidized training fee includes the massive training manual, multiple meals, ample coffee, and the Association of Food and Drug Official (AFDO) certificate (a $130 value—not including space rental or instructor fees!). The AFDO training certificate satisfies FSMA Produce Safety Rule training requirement.

EVERYONE is invited: Regardless of scale, annual sales, or market outlets, all produce growers can benefit from learning about integrating practical produce safety practices on a working produce operation. Technical assistance providers, educators, and regulators are also invited and will benefit from this training. Whether you are a covered farm fully subject to Produce Safety Rule (PSR) regulations, or an exempt farm required to keep certain records related to your exemption, all aspects rule compliance will also be covered during this training.

The Training Schedule at a glance:
Day One (November 7, 8:30am–5:00pm) will provide an introduction to the FSMA Produce Safety Rule, employee health, hygiene and training requirements, and information about management of soil amendments as well as domesticated animals and wildlife. Includes on-farm exploration to apply concepts in the field.
Day Two (November 8, 8:30am–5:00pm) will cover agricultural water, postharvest handling and sanitation, and writing produce safety plans. Includes on-farm exploration to apply post-harvest concepts.

View more details and registration visit:  PSA Training Registration via Regonline

Building a Hoop House in One Day!

A fun day of learning during a hoop house install during one single day by Nifty Hoops at Bread & Butter Farm in Shelburne VT.

See photos from the day on our flickr page here: https://flic.kr/s/aHsm4yUQUL

IMG_7404

Like Nifty Hoops on facebook! https://www.facebook.com/NiftyHoops/

Visit Nifty Hoops website: http://niftyhoops.com/

Nifty Hoops has their own YouTube Channel! https://www.youtube.com/channel/UCj0g…

Check Out Bread & Butter Farm! https://www.facebook.com/breadandbutt… http://www.breadandbutterfarm.com/

 

 

Improved Ventilation for High Tunnels

I have received many inquiries about how to improve ventilation of high tunnels from growers with tunnels that have only roll-up sides. The issues they are facing tend to be either high temp, high humidity or both, leading to plant stress or disease. These situations tend to be in less than ideal sites for ventilation and/or temperature control. For example, crowded lots with trees or other significant wind breaks close to the tunnel, high southern exposure (which can be good of course), and/or simply calm sites that provide little ventilation.

Keenan Meier Shutters with flanged seal highlighted.

Roll-up sides alone tend to work for tunnels on sites with generally good air flow. Diffusion between inside and outside does happen, of course, but is slow and unlikely to achieve good ventilation along the center of the tunnel, especially with dense vegetation later in plant maturity. But, I think of a tunnel in this instance a bit like a wood stove. Without a chimney-effect natural draft, you’re really only getting ventilation from the sides and only then if there is a decent breeze. Warmer air and, therefore, humidity will tend to collect in the canopy and peak.

Passive wax cylinder louver actuator. [Photo Credit: http://www.littlegreenhouse.com/accessory/vent2.shtml]
This probably is OK in many sites for most crops. But not always. In many cases gable vents will improve ventilation by acting as outlets for warm humid air in warmer seasons and by allowing for low volume ventilation in colder weather. I recommend a simple 24″x24″ gable vent (for a 30’x96′ tunnel) on each end wall, with a thermostatic wax cylinder actuator like the ones made by J. Orbesen Teknik APS available from LittleGreenhouse.com., FarmTek, and Agricultural Solutions among others  The actuators require no electricity, are relatively inexpensive and are passively controlled by the wax cylinder based on temperature.

At the very least, when building end-walls consider framing in a rough opening to accept a 24″x24″ in the end wall so that a future install is easier. If you want to skip the expense of a louvered, wax cylinder system, you can use a manually-controlled sheet of plywood to open and close the vent. If you go with a louvered vent, seek one that has a flanged seal it closes against. Keenan Meier, and Munters-Euroemme has such flanged, louvered dampers.

Munters Euroemme fan with flanged seal being pointed out.

These have zero daylight when closed which results in a solid seal. Most others on the market that I have seen have no such closure seal.

Fans

Fans in greenhouses and high tunnels generally perform two tasks: (1) circulation / mixing / stirring and (2) ventilation.

  1. Circulation / Mixing / Stirring – Sometimes referred to as horizontal air flow or “HAF” fans, these fans are generally hung from the inside horizontal structural tubing.  They only mix the air.  The benefit of this is consistent, well distributed growing conditions.  It also ensures that your control sensors are seeing the “average” conditions of the space. Remember that HAF fans work to mix the space (circulate the air) but don’t significantly improve ventilation. HAF combined with roll up sides can do the trick, but the site is the key. There needs to be a steady cross breeze for any significant air exchange to occur.
  2. Ventilation – Ventilation, or “exhaust” fans provide air exchange between the inside and outside. This is really important in controlling temperature (cooling) or humidity (drying).  The only way to remove heat or humidity from a standard high tunnel or greenhouse is by actively removing air from the space and bringing in outside air.  Ventilation (cooling) systems are covered very well by Bartok and Aldrich (p. 70).  Basic rules of thumb for ventilation are 8 CFM/ft2 (of growing space) for summer cooling and 2 CFM/ft2 for cooler months.

References:

Bartok, J., & Aldrich, R. (1994). Greenhouse Engineering, NRAES – 33. Natural Resource, Agriculture and Engineering Service (NRAES). Retrieved from http://host31.spidergraphics.com/nra/doc/Fair%20Use%20Web%20PDFs/NRAES-33_Web.pdf

Rats (and other rodents)

Download the PDF version of this page here!

When considering storage rooms, wash and pack sheds with growers there is one topic that is sure to strike a nerve: RODENTS.

This document is intended to provide summary information about measures you can take to reduce crop losses from these pests.  It is the result of a review of current literature on the topic and feedback from the Listserv of the Vermont Vegetable and Berry Grower’s Association (VVBGA). This document includes both active measures (traps, rodenticides, FSMA compliant cats and ball pythons, etc.) and passive measures (sealing, doors, packing, hardware cloth, novel construction, accepting the loss, selling everything early). But why are these creatures so challenging?  Here’s some background1:

House Mice Can

  • Enter openings larger than 1/4 inch
  • Jump as high as 18 inches
  • Travel considerable distances crawling upside-down along wire
  • Survive and reproduce at a temperature of 24°F if adequate food and nesting material are available.

Rats Can

  • Crawl through or under any opening higher or wider than 1/2 inch
  • Climb the outside or inside of vertical pipes and conduits up to 3 inches in diameter
  • Jump from a flat surface up to 36 inches vertically and as far as 48 inches horizontally
  • Drop 50 feet without being seriously injured
  • Burrow straight down into the ground for at least 36”
  • Swim as far as 1/2mi in open water, dive through water traps in plumbing, and travel in sewer lines against a substantial water current.

As one grower put it, “To deal with rats, you’ve got to think link a rat!”

Bottom Line

Cleanliness and Sanitation – Keep food sources well contained and sealed up, reduce “harborage” (places they can hide and live including weeds around the edge of a building), minimize available standing water. In short, make it unappealing and uncomfortable for them.

Rodent Deterrent Construction – Keep them out of the building. [References 1-3 provide very detailed guidance and novel, passive and relatively inexpensive construction ideas] Some examples from the references include keeping all wood products like cardboard, roots, or lumber off the ground and away from the building. Installing proper drainage with sand, stone and proper slope away from your building helps reduce moisture which can carry other pests like beetles and termites. Think about your exterior landscaping and its ability to trap moisture against the building. Keeping grass and weeds trimmed won’t leave a place for rodents to hide and travel. Think about all possible points of entry, sills, doors, windows, roofs. Mice can sneak into small holes and cracks so do your best to seal up all possible points of entry.

Population Reduction — Bait, trap, kill.

Using snap traps, sticky pads, poisonous bait are all the most effective ways of dealing with a rodent problem [References 5-7].

Responses from the VVBGA LISTSERV 

The following are responses from Vermont growers. These are some of their challenges and solutions related to rodents on their farms.

  • I have had over 20% of my sweet potatoes damage by voles.  Usually the largest sweet potatoes are the ones half eaten.  The next year I put five “yard windmills” in the sweet potato bed, 100 ft. long, along with a half stick of gum under the black plastic by each plant – cheap gum from the discount food store.  Both were done after I removed the row covers and before the vines spread. That reduced the damage to less than 5%. Very anecdotal and empirical data but worth exploring.  Supposedly the voles do not like vibration of the windmill and eating the gum gives them a bellyache, if fatal I do not know.  Bigger windmills, four inches in diameter and larger, with metal post seem to work better.  How much gum is actually needed I do not know. A SARE  grant in your future.
  • Not the cheapest retrofit, but have had the best luck with making all walls tin or concrete, and having rat traps permanently set at every overhead door jamb, since the seal is not 100%.  Ventilate with in-wall intake and exhaust fans instead of opening doors.
  • I recently tried the tin cats and was happy. Baited them by putting small amount of oats in the trap and tilting it so the grain slid to the end where the screen was. After the mice got a few seed through the screen, they were drawn into the trap to get the remainder. Two mice in the same trap on the first night. The downside is that you have to clean out all the grain each time so it doesn’t hamper the trap mechanism. Have used Contract waxy block in bait stations for at least 4 years. Switching to a different bait because I think they are starting to get a resistance.
  • I’ve been using that old root cellar all winter for 3 years now without any rodent problems. The process of having someone cement hardware cloth over every crack and crevice was time-consuming but really seems to have worked. I think I finally got rid of the rats in my toolshed through a combination of trapping and disturbing their nesting spots. I’m curious about rodent solutions that apply to the field and high tunnel. I’ve tried to keep cats but the fishers get them.
  • I have not had a single animal in the new barn that I built with the 12” concrete knee wall. I partly contribute the success to the fact that I do not set the bins on the ground. They are filled on the trailer and go directly from the trailer to the barn. This reduces the chance that a hitchhiker will take a ride into the barn.

  • We are a very small pumpkin farm and don’t have the storage needs for food, but I use lots of snap traps and dump those little, dead vermin bodies while wearing a happy smile!
  • We have only killed rats by accidentally moving a pallet onto one. Can’t bait them. They are very intelligent.
  • “We have a great barn cat and a Jack Russell terrier for our farm.”
  • Mice – kernel of corn wedged into mousetrap trigger covered in peanut butter. Rats – same as above but do not the set the trap for several nights and remove all other food sources (in chicken hutch empty all food containers) then set the trap.  Putting a milk crate over the trap prevents chickens, cats, dogs from getting caught.  Also works with chipmunks, and occasionally with red squirrels. Voles – hard to trap, run them down and stomp.

REFERENCES

  1. Baker R., Bodman G. and Timm, R. 1994. Rodent-Proof Construction and Exclusion Methods. The Handbook: Prevention and Control of Wildlife Damage. Paper 27.  http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1025&context=icwdmhandbook
  2. Hoddenbach, G., Johnson, J., Disalvo, C. 1997. Rodent Exclusion Techniques. A Training Guide for National Park Service Employees. National Park Service. http://www.ehs.ucsb.edu/files/docs/e
    h/ihrodentexclusion.pdf
  3. Simmons, S. 2005. Pest Prevention Construction Guidelines and Practices. CASBO Journal. http://www.cdpr.ca.gov/docs/pestmgt/pubs/casbo_article.pdf
  4. UMass Extension. 2008. Rodent Control on Farms. Fact Sheet – https://ag.umass.edu/sites/ag.umass.edu/files/fact-sheets/pdf/RodentControl08-44.pdf
  5. University of Maryland Extension. 2014. Rodent Control on Small Poultry Farms. Fact Sheet. https://extension.umd.edu/sites/default/files/_docs/publications/FS-
  6. 985%20Rodent%20control%20on%20small%20poultry%20farms.pdf
  7. Pierce, R. 1982. Bait Stations for Controlling Rats and Mice. Fact Sheet G-9444. University of Missouri Extension. http://extension.missouri.edu/p/G9444
  8. Vantassel, S. M., Hygnstrom S. E. and Ferraro, D. M. 2012. Bait Stations for Controlling Rats and Mice. Fact Sheet G1646. https://wildlife.unl.edu/pdfs/bait-stations-controlling-rats-mice.pdf.

Pumps and Pipes

A Taco 007
A Taco 007, shaken not stirred.

“Will the 007 be enough?”  is a common question in early spring as greenhouses around the region fire up and we do our best to keep seed trays and their cargo warm on the still-cool nights.  My mind instantly goes to “which movie?” And then I crash back to earth and realize this is a question about pumps and I am not Q. Continue reading Pumps and Pipes

Thermostats for Agriculture

I am often asked by growers and processors to recommend a thermostat for a greenhouse, cooler, or postharvest process use.  There are many to choose from and their specifications can be confusing. It is important to remember just what a thermostat does. It is essentially no different from the light switch on the wall with one very significant exception.  Instead of depending on a person to switch it from ON to OFF, we use a temperature measurement.  The accuracy of both the temperature setpoint (what you set) and the actual temperature (what the actual condition is) can be critical for production quality and energy efficiency. Continue reading Thermostats for Agriculture

Calculating Greenhouse and High Tunnel Heat Loss

I am often asked by growers to help estimate what size heater is needed for a greenhouse or what minimum temperature their high tunnel will reach at a certain outside temperature.  Below are some tools to help you do this yourself.  I have presented them in a range of complexity depending on how much you really want to get into the math.  Enjoy.

1. SIMPLEST – Online greenhouse heat load calculator. http://www.greenhousemegastore.com/greenhouse_btu_calculator This online calculator allows you to enter the dimensions, construction material and temperatures you are interested in and it estimates the heat (and cooling) load.

2. LITTLE MORE COMPLEX – VirtualGrower – http://ars.usda.gov/services/software/download.htm?softwareid=309. This is a free software tool from USDA ARS that is a bit more complicated than the simple form above. But there is benefit to the complication. As with any analysis, the more you put into it, the more you get out of it. VirtualGrower allows easier management of multiple “what-if” scenarios, includes regional weather and light data automatically, and accounts for heating and ventilation systems. You may find it interesting and useful.

3. HEAVY LIFTING, but FULFILLING – Do the calculations yourself! The formulae behind all of the tools above are well described in “Greenhouse Engineering, NRAES-33” by R. A. Aldrich and J. W. Bartok. Available here as a PDF: http://host31.spidergraphics.com/nra/doc/Fair%20Use%20Web%20PDFs/NRAES-33_Web.pdf. See p. 65-71 specifically.

4. HEATING BENCHES, ROOT-ZONE or GROUND – When heating the root zone locally, different heater sizing approaches are needed.  This is covered well by “Root Zone Heating Systems” in Wilkinson KM, Haase DL, Pinto JR, technical coordinators. National Proceedings: Forest and Conservation Nursery Associations—2013. Fort Collins (CO): USDA Forest Service, Rocky Mountain Research Station.Proceedings RMRS-P-72. 62-65. Available at: http://www.fs.fed.us/rm/pubs/rmrs_p072.htm.

LED Lights – Status, Cost/Benefit and Pro’s and Cons

I have been receiving several inquiries recently on supplemental lighting for greenhouse production. The most common question is “Should I install LED lights to support growing?”
I have found one report to be the most complete and current on this topic and wanted to share it here.

Economic Analysis of Greenhouse Lighting: Light Emitting Diodes vs. High Intensity Discharge Fixtures by Jacob A. Nelson and Bruce Bugbee. Published: June 6, 2014. DOI: 10.1371/journal.pone.0099010. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0099010. Erik Runkle at Michigan State University also summarizes some of this work in Greenhouse Product News here.

There are some industry responses to this including this one from Inda-Grow. And a recent USDA report is somewhat contradictory in its findings here.

There is a also a nice summary by Robert Morrow in Hort Science (HortScience December 2008 vol. 43 no. 7 1947-1950) available here.

Nelson and Bugbee conclude;

The most efficient HPS and LED fixtures have equal efficiencies, but the initial capital cost per photon delivered from LED fixtures is five to ten times higher than HPS fixtures. The high capital cost means that the five-year cost of LED fixtures is more than double that of HPS fixtures. If widely spaced benches are a necessary part of a production system, LED fixtures can provide precision delivery of photons and our data indicate that they can be a more cost effective option for supplemental greenhouse lighting.

Manufacturers are working to improve all types of lighting technologies and the cost per photon will likely continue to decrease as new technologies, reduced prices, and improved reliability become available.

My take-away from all of this; LED’s have a higher initial cost, can have lower recurring costs, can be more effective for specific physiological benefit, and can support certain production layouts.  But the cost/benefit does not seem to pencil out quite yet.