Fruit Crops Edition - Blueberry Section

Seasonal updates on diseases, insects, weeds impacting small fruit (blueberry, cranberry, and wine grape). Fruit Pest Alerts are also available via this category feed.
 
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COVID-19 Guidance For Farmworkers & Employers

An Important Message from Secretary Fisher (May 6, 2020)

“As mentioned during the Governor’s press conference this afternoon by Health Commissioner Judith Persichilli, a group led by the Department of Health, working in coordination with the Departments of Agriculture and Labor, is finalizing a Guidance Document, “COVID-19 Guidance for Migrant and Seasonal Farmworkers, Their Employers and Housing Providers.” As stated by the Health Commissioner today, this document is expected to be rolled out at the end of this week, with further communication about it coming next week.”

Details will be shared as soon as this guidance document is available.

Frost Protection in Orchards – What Should You Monitor?

By Hemant Gohil and Megan Muehlbauer

The weather forecast for the next few days indicate subfreezing temperature in several parts of New Jersey. In fruit crops, such events during the flower bud development, can cause crop loss which could vary from minor loss of quality and quantity to a total crop loss. Recently, frost events seem to be occurring more frequently. These events have been driven by warmer spring temperatures pushing bud growth earlier, making blossoms more vulnerable to frost damage.

What to monitor before active frost protection?

Frost damage occurs when plant tissues are exposed to subfreezing temperatures (Figure 1). However, it is the co-occurrence of other factors that determines the extent of the damage. All these factors should be monitored, and will assist in determining which frost protection method to employ and its duration.

Frost damage in apple

Figure 1. Frost damage in apple following the freeze event in 2010 in Pennsylvania (Photo by R. Crassweller).

Bud Stage: Regular monitoring of the bud development stage beginning at bud swell will help in determining the actual threat of frost damage. Critical temperatures have been researched and calculated for each bud development stage. For example, in an apple orchard, at 24°F, one can expect up to 90% crop loss at ‘first pink’ stage, but only marginal to zero percent loss at green tip stage at the same temperature. An example of the critical temperature for some of the most common pome and stone fruit crops In New Jersey is available at https://www.canr.msu.edu/news/critical_spring_temperatures_for_tree_fruit_bud_stages  Note that the critical temperature for damage at a particular bud stage may vary by 4 or 5⁰F depending on temperatures during the previous few days before the cold event.

Type of frost event: There are two types of frost:  Advective and Radiative frost.  Advective frost occurs when a large mass of cold dry air moves in from another region and replaces warmer air such as during a polar vortex. The rapid movement of air aids this, and there is generally an absence of an inversion layer, creating the potential for a prolonged event. Frost protection will generally be not effective during an advective frost.  Conversely, radiative or radiational frost occurs when there is a rapid loss of heat from the ground, usually with a cloudless open sky, dry air, little wind and the likely formation of an inversion layer. This frost is relatively manageable with frost protection methods.

Inversion Layer: A strong inversion layer can be a source of warmer air, and could have a substantial difference in temperature than that closer to the ground.  For this reason, inversions need to be closely monitored.

Table of wet bulb temp

Table 1. An example of determining wet bulb temp using ambient temp and dew point. Courtesy, Don Smith, Penn State University

Air Temperature: Frost can occur when the ambient temperature dips below freezing (32°F). The hourly rate of falling temperatures and the lowest forecasted temperature should also be monitored. However, temperature experienced by trees will not necessarily be the same as the reported ambient temperature.  To measure the temperature of the flower buds, farmers must take into account the cooling effect of evaporation of the moisture on the trees which is referred to as the wet-bulb temperature. Generally, the wet bulb temperature will be a few degrees lower than the dry bulb temperature except at the 100% RH. Table 1 provides an example of determining wet bulb temperature using the ambient temperature and the dew point. Hand-held and digital psychrometers can be used in the field to determine the wet bulb temperature.

Recently, Knox et al. (2017) at the University of Georgia showed that wet bulb temperature can be simply derived by ‘subtracting one third the difference between ambient temperature and dew point, from the ambient temperature.’ Modern frost alarms measure wet bulb temperature, which can directly transmit real time data to the user’s mobile phone or computer.

Dew point: Dew point is commonly reported as the atmospheric temperature below which water droplets begin to condense, forming dew. At low temperatures, the moisture in the air transitions from a gas to a liquid, as air temperature reaches the dew point. A higher dew point is associated with relatively slow drops in temperature, and vice versa. A lower dew point also generally means surface moisture will evaporate quicker.

Cloud coverage:  Clear skies normally result in lower low temperatures than when there is cloud cover trapping radiant energy from the ground.

Wind Speed: Wind will determine the rate of loss of thermal energy. Almost all Frost Protection methods will have reduced efficiency at wind speeds above 10 mph, and are therefore not recommended when winds are above 10 mph.

Effective Frost Protection requires weather stations and sensors for each of the fields you are seeking to monitor and protect.  Data from a nearby weather stations may not always be reliable.  On-farm weather stations are the most accurate source of weather data, and should be linked with a frost alarm.

Literature Cited:

Knox JA, Nevius DS, and Knox PN. 2017. Two Simple and Accurate Approximations for Wet-bulb Temperature in Moist Conditions with Forecasting Applications. Bulletin of American Meteorological Society. Sept Issue: 1897-1906. https://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-16-0246.1

Take home message: 

  • Monitor both your temperature and relative humidity to determine the wet bulb temperature. Remember nighttime temperatures often dip BELOW predicted temperatures, do not GAMBLE.
  • Determine what bud stage your tree fruit are at.
  • If you suspect you are at risk of a nighttime frost event, monitor the weather report for the likelihood of an inversion layer.
  • hink you have a potential for a frost event in your orchard, utilize appropriate frost protection measures.

Tree Fruit IPM Report for May 5, 2020

 

Tree Fruit Phenology: Tree Fruit Phenology remains advanced, but development is slowing. In southern counties peach orchards are at Shuck Split to Shuck Off. Pears are past Petal Fall. Red Delicious was about Full Bloom on 4/25 and is late bloom/Petal Fall on May 4. Other varieties still have considerable bloom. Cherries are just past full Bloom. [Read more…]

On-Farm Direct Marketing in 2020 Webinars – Every Tuesday Night in May

Rutgers Cooperative Extension Agricultural Agents are hosting a 4-parFruit standt webinar series, every Tuesday in May from 7:00-8:00PM to assist farmers with on-farm direct marketing operations to develop strategies for the 2020 season. This 4-part, weekly program will present and discuss the following topics:

Session 1 (May 5th): Maintaining Social Distancing and Safe Food Handling Practices: Guidance for Farm Markets – Wesley Kline, Ag Agent, RCE of Cumberland Co. and Meredith Melendez, Ag Agent, RCE of Mercer Co.

Session 2 (May 12th): Sales and Distribution Strategies – William Bamka, Ag Agent, RCE of Burlington Co. and Stephen Komar, Ag Agent, RCE of Sussex Co.

Session 3 (May 19th): U-Pick Operation Guidelines under COVID-19 – Meredith Melendez, Ag Agent, RCE of Mercer Co.

Session 4 (May 26th): Farmer Panel – Strategies We Are Using – (Farmers TBD) Moderators: Michelle Infante-Casella, Ag Agent, RCE of Gloucester County and Meredith Melendez, RCE of Mercer Co.

To Participate online for All 4 Events:
Use the link:  https://go.rutgers.edu/k0d59m8h

Or join by phone:
+1-650-429-3300 USA Toll
Access code: 226 795 368 # and then # again

We suggest visiting at least 15 minutes before the session start time to confirm system requirements 

For more events hosted by Rutgers Cooperative Extension check out the NJAES Events Calendar.

Ask the Ag Agent Weekly Online/Call-In Forum and New Web Page

Ask the Ag Agent was created when COVID-19 forced a new normal in communications nationwide. Rutgers Cooperative Extension Agricultural Agents working with “Ask the Ag Agent” education and outreach are cAsk the Ag agentommitted to the agriculture industry and all interested in growing plants, raising livestock and essential resources related to agriculture. The program now features a new Ask the Ag Agent website with more information.

Farmers and others are welcome to join a weekly teleconference each Wednesday night from 7:00pm-8:00pm. Weekly events are hosted by Rutgers Cooperative Extension Agricultural Agents working with the farming industry.

This call-in/WebEx event features updates on farm management, crop conditions, farm industry observations, agricultural agency programs and other topics discussed by farmers, agricultural agents and other agricultural service providers.

Hosted by Bill Bamka, Stephen Komar, Michelle Infante-Casella and Meredith Melendez, this weekly communication provides a forum for discussion for farmers and all involved in NJ agriculture. Agricultural agency personnel, non-profit organizations and others have participated and added additional discussion with farmers.

This event and other events hosted by Rutgers Cooperative Extension can be found on the Rutgers NJAES Events website.

To join the “Ask the Ag Agent” forum each week on a computer/tablet/smartphone via the WebEx Videoconference:

Use the URL: https://go.rutgers.edu/rc9n3kxtiPhone

To join the “Ask the Ag Agent” each week on the Phone:
Call: (650)-429-3300
Access Code: 799-743-872 # followed by #

Penn State Webinar: H-2A Agricultural Workers in Times of Uncertainty

Penn State Cooperative Extension is hosting a free webinar to discuss the H-2A program in Pennsylvania. This may be helpful for NJ Farmers to listen in to find any updates or tips on how to handle this agricultural worker program. You must register to join this online event. In order to register you will need to create an account on the Penn State advertisement page.

Webinar Date: Thu., May 7, 2020
(6:30 PM – 8:00 PM ET)

Registration deadline: May 7, 2020
5:30 p.m.

COVID-19 mitigation efforts, including international travel restrictions and consulate closures, have disrupted the normal functioning of the H-2A visa program for temporary workers. These disruptions to the H-2A program raise questions about the timely arrival of guest workers and the impact on essential food and agricultural businesses. The H-2A Agricultural Workers in Times of Uncertainty Webinar will provide answers and guidance to the many questions surrounding this topic.
The dangers of COVID-19 itself similarly raises questions around how to protect the health and well-being of H-2A visa holders. As front-line workers, the protection of their livelihoods and health are integrally tied to the protection of public health.

Penn State Extension will be holding a townhall-style webinar to address these topics, and to provide answers and guidance to these questions. Join us as we hear from a panel of subject matter experts, including Brook Duer, Staff Attorney at the Penn State Center for Agricultural and Shale Law; Grant Meckley, Pennsylvania Keystone Health’s Agricultural Worker Program; Scott Sheely, Executive Director of the Lancaster County Agriculture Council; and Richard Stup, Agricultural Workforce Specialist at Cornell Cooperative Extension. Also joining us will be Alyssa Charney, Agriculture Legislative Assistant from Senator Casey’s Office.

Attendees will have the opportunity to either send in questions ahead of time, or during the webinar itself, for a Q&A session following the panelists’ overview and update on the H-2A visa program.

There is no cost for this webinar, however registration is required to receive the webinar link. To go to the registration page you can also see https://go.rutgers.edu/if9tsm4h.