April grower checklist (April 1, 2014)
1. Maintain vigilance for late frosts; April may continue to be cool. Be sure to sign up to receive strawberry advisories and weather alerts (send a message to mj2@ lists.ncs.edu with the following message in the message body: subscribe berry-mg). Advisories are posted at //strawberries.ces.ncsu.edu/
2. Leave overhead irrigation in field for evaporative cooling of blossoms in the first half of April and monitor daily forecasts closely in April and May for high temperatures that can be damaging to open blossoms – consider sprinkler irrigation for evaporative cooling to protect fresh blossoms from temperatures above 87/88°F. Growers using heat mitigation measures were successful in saving much of their crop from early and mid-April heat waves in 2002 and 2010; it seems that 2-3 days of extreme heat during pre-bloom and bloom have the potential to cause greater losses in Camarosa than Chandler.
3. During warm/hot days in the harvest season you can drip irrigate for a few hours in the early morning (around sunrise) to keep plants “fresh” and to minimize the possibility of heat damage to late blossoms and berries that are directly exposed to the sun. Do not use overhead sprinkling for evaporative cooling once picking is underway. In addition to being “proactive” in your drip irrigation on warm/hot days, be sure to “pick closely” as fully red berries on the edges (shoulders) of the bed are highly susceptible to sun-scalding. “
4. Never allow strawberry plants to wilt. Provide drip irrigation on a daily basis in warm/hot weather; in milder conditions, every other day is fine. Strawberries need an average of 1 inch of water per week in order to grow adequately; in warmer conditions, 1.5 inches of water per week per acre is needed. One inch of water per week equals 27,154 gallons/acre, or 3,789 gallons/acre/day. Don’t let the shoulders of the beds become dry. In spring 2014 we are noticing that row-covered fields are further ahead than non-covered plants by as much as 10-14 days – the larger, more advanced plants will need close water and fertility management!
5. If you get hail damage in April/May, be sure to use a fungicide afterwards to reduce growth of fungi that take advantage of the wounded tissue to colonize the berry (so-called opportunistic and secondary pathogens), e.g., Switch, a broad spectrum fungicide with 12 hr REI and 0 day PHI. If Switch cannot be used, a broad spectrum product like captan would also work well. Warm, dry weather also helps the wounds on green berries to heal.
6. Scout fields for mites, insects, and diseases, especially Botrytis. Protecting the flowers is the key to managing Botrytis (gray mold), which infects flowers in the spring and there moves on to the fruit. Botrytis cinerea historically has a high potential to develop resistance, and recent data suggest some fields have a high percentage of strains resistant to several important fungicides. It is important to limit the number of times fungicides of the same class are applied in 1 year; and sample gray mold populations for their resistance profile through Clemson University. For instructions to submit your samples see: //strawberries.ces.ncsu.edu/2013/06/instructions-for-collecting-and-mailing-gray-mold-samples-to-clemson-for-fungicide-resistance-profiling/
7. Send suspicious-looking NC Plant Disease and Insect Clinic. When the weather “turns” and becomes warmer, you often see some plants wilting or collapsing – it is important to get these to a professional lab for correct diagnosis.
8. Send in leaf samples for plant tissue testing every 14 days from the early bloom period through the first half of the harvest season. Fertigation is generally done on a weekly basis for 10-12 weeks. Use the rate of N recommended in your most current plant tissue report.
9. Estimate when the crop will ripen so that you can anticipate yields; schedule and train sales people; coordinate promotions, and picking labor accordingly – watch for announcements and updates from your local Department of Agriculture on crop ripening and different promotional programs.
10. If weather conditions are cooler than normal in March, like this year in the Carolinas and most of the mid-South, expect up to 40 days from open blossom to a fully red-ripe fruit for the first 10-14 days of blooms. But, once the weather warms up, it usually takes about 28-30 from the open blossom stage to ripe berry.
11. Provide hand-washing facilities and single-use paper towels for both workers and customers. Have porta-potty service delivered and emphasize proper sanitation for farm labors and customers.
12. Put out signs on the roadside to direct customers to your fields when berries are ready. Be sure to post a good message on your telephone answering machine. Keep fields picked every 2-3 days. Post signage on prices clearly. Figure out a system to collect customer names, addresses and emails for your mailing list.
Dr. E. Barclay Poling
Interim Executive Director, NC Strawberry Association Inc.
& Professor Emeritus (Strawberry Plasticulture Researcher)
Department of Horticultural Science
Campus Box 7609, 162A Kilgore Hall
NC State University
Raleigh, NC 27695-7609
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