Multi-State Strawberry Weather Update on Sunday Afternoon (4:25pm, 3/19/17)

— Written By Barclay Poling

Good afternoon,

I was just noticing this afternoon how the Monday minimum temperature map for NC has changed since yesterday. Compare Fig. 1 (current forecast for Monday) to yesterday’s (Fig. 2)

NC minimum temperature map

Fig. 1. The latest minimum temp map for NC shows colder temperatures tomorrow morning for areas like the northern piedmont than were in the forecast yesterday (Fig. 2). The dark blue areas represent minimums of 32-34. Just yesterday, areas like Danville were in the lighter blue zone of 34-36. Not anymore!

minimum temperature map

Fig. 2. Forecast made yesterday for Mon morning.

minimum temperature map

Fig. 3. Note the very low minimums for this Thursday morning as well.

We’ve had a situation in the last several days of getting forecasts on the “high side” of what actually has been happening, and so I am a little more worried about tomorrow morning this Sunday afternoon than I was just a day ago. Still, the minimum temperatures for Monday are “not that bad,” compared to what we went through last week! Some growers will likely just sit this one out due to losses of blossoms and popcorns to last week’s freezes. For growers who managed to hang on to their blooms and “green fruit,” I would surely approach this frost tomorrow morning with a great deal of caution, and don’t be too surprised if the minimums are lower than what is in the forecast today. One good thing I see is that we are not dealing with incredibly low dew points, like last Thur/Fri.

Widespread “white frost” is expected in many areas tomorrow, and in just glancing at a sample of AWIS Detailed Hourly Forecasts for Greensboro, NC, it looks like a minimum air temp of 33 expected, and that dew points are in the mid-20s. For this area, AWIS is making a forecast for FROST at about 5 a.m. Growers in this area can watch closely for formation of ice crystals on solid objects like a lay flat hose, or edge of a row cover, as their visual cue as to when to start sprinkling.

We did have some scattered showers and even brief snow in some areas this morning, and if your row covers are not drying out that well by this early evening, it would be wise to monitor bloom temperatures underneath the covers tonight with digital thermometer, and if you see those temperatures slipping below 32, you may want to be ready to run some sprinkling on top of the covers before those blossom temperatures drop below 30 F. And, just to be safe, take a look underneath those row covers in the early morning to make sure there is no frost occurring beneath the cover – this actually happened in some Eastern NC locations this past Sun/Mon. When this sort of thing occurs (frost under covers), it does “shake you up,” and cause a loss of confidence in row cover protection. But, the whole premise for row covers to work properly in a frost situation is that the covers are going into the evening DRY. And, whenever  there is a precipitation event prior to a cold event (like tonight), we don’t want to assume that a moist and/or frozen row cover will confer the same level of protection to open blossoms as a DRY cover. Thus, the important need to closely monitor blossom temperatures if covers have been “compromised” by some form of precipitation event prior to the cold event, and to stick a flash light under the cover a few hours before sunrise to make sure you don’t see anything strange happening, like a frost under the cover. If you do see something like this happening (frost forming underneath cover), go ahead and run the drip system to add some heat back into the system, or run sprinklers on top of the cover.

NC NC_7 day Min Temp Forecast

10-DAY DETAILED HOURLY WEATHER FORECASTS

Ahoskie-Tri-Cou Albemarle_AP Andrews Asheboro
Asheville_Munic Beaufort-Michae Boone_NC Burlington-Burl
Cape_Hatteras_AG Chapel_Hill-Hor Charlotte Cherry_Point
Clinton_NC Concord_NC Currituck_NC Edenton-Northea
Elizabeth_City Elizabethtown_NC Erwin-Harnett_C Fayetteville_AP
Fort_Bragg/Simm Franklin/Macon_C Gastonia-Gaston Goldsboro_AFB
Goldsboro_NC Greensboro Greenville_AP_NC Hickory
Jacksonville Jacksonville_(A Jefferson_AP_NC Kenansville-Dup
Kill_Devil_Hills Kinston_AP Lexington-David Lincolnton_AP
Louisburg_NC Lumberton_AP_NC Mackall_AAF Manteo/Dare_Co
Maxton Mcalf_Bogue_Fiel Monroe_AP_NC Morganton-Morga
Mount_Airy-Moun New_Bern North_Wilkesbor Oxford_NC
Piney_Island_Bom Pope_AFB Raleigh-Durham Reidsville_AP
Roanoke_Rap_AP Roanoke_Rapids_R Rockingham_NC Rocky_Mount-Wils
Roxboro_AP Rutherfordton Salisbury-Rowan Sanford_NC
Shelby_AP_NC Smithfield_AP Southern_Pines Southport_NC
Statesville-Sta Tarboro_AP Wadesboro_AP Washington-Warr
Whiteville_NC Wilmington_AP_NC Winston-Salem

MD Md Outlook

10-DAY DETAILED HOURLY WEATHER FORECASTS

Aberdeen Andrews_AFB Annapolis_Naval Baltimore_Sci_Ce
Baltimore/Wash Cambridge/Dorche College_Park_AP Cumberland_AP
Easton_MD Fort_Meade Frederick_MD Gaithersburg_AP
Hagerstown_AP Leonardtown Middle_River Oakland_MD_AP
Ocean_City_AP Patuxent_River Salisbury Stevensville_AP
St_Inigoes/Webst Washington_DC_AP Westminster_AP

Virginia Va Temp Outlook

10-DAY DETAILED HOURLY WEATHER FORECASTS

Abingdon Ashland_VA Charlottesville Chesapeake-Ches
Culpeper Danville Dublin/New_Riv Emporia_VA
Farmville Fentress_Naval_A Fort_Belvoir/Da Fort_Eustis/Fel
Franklin/J_B_Ro Hillsville Hot_Springs/Ing Jonesville_AP
Langley_AFB Leesburg/Godfre Louisa-Louisa_C Lynchburg
Manassas_Muni(A Marion/Wythev Martinsville Mecklenburg/Bru
Melfa/Accomack Newport_News Norfolk_Hampton_ Norfolk_NAS
Norfolk_VA Oceana Orange_VA Petersburg_(AWO
Quantico Richlands_AP Richlands_VA Richmond
Richmond_Chester Roanoke Shannon_Arpt Stafford_AP_VA
Staunton-Shenan Suffolk-Suffolk Tappahannock_AP Virginia_Tech_A
Wakefield_AP Wallops_Island Warrenton_Fauqui Washington_Dulle
West_Point_VA Williamsburg_VA Winchester_Rgnl Wise/Lonesome_P

South Carolina SC Temp Outlook

10-DAY DETAILED HOURLY WEATHER FORECASTS

Aiken_AP Anderson_Co_Air Barnwell_AP Beaufort_Cnty_AP
Beaufort_SC Bennettsville_Je Camden_AP Charleston_Exec_
Charleston_Muni Cheraw_AP Chester_AP Clemson-Clemson
Columbia-Columb Columbia/McEnti Columbia_Metro Conway_AP
Darlington Florence_SC Georgetown_AP_SC Greenville_Donal
Greenville_Down Greenville-Spart Greenwood-Green Hartsville_AP
Hilton_Head_AP Kingstree_AP Lancaster-McWhir Laurens_AP
Manning_AP Marion_AP_SC Moncks_Corner_AP Mount_Pleasant_A
Myrtle_Beach Newberry_AP North_Myrtle_Be Orangeburg-Oran
Pickens_AP Rock_Hill Spartanburg_Down Summerville_AP
Sumter_AP Sumter_SC Walterboro_AP Winnsboro_AP

Georgia Ga Temp Outlook

10-DAY DETAILED HOURLY WEATHER FORECASTS

Albany_Municipa Alma/Bacon_Co Americus_AP Athens_Municipa
Atlanta/DeKalb Atlanta/Fulton Atlanta_Intl_Ar Atlanta_Paulding
Augusta/Bush_Fi Augusta_Daniel_F Bainbridge_GA Blakely_AP
Brunswick_GA Brunswick/Glync Canton_GA Carrollton_AP
Cartersville_AP Claxton_AP Columbus_GA Covington_GA_AP
Dalton-Dalton_M Douglas_Muni Dublin/WHBarron Fitzgerald_AP
Fort_Benning Ft_Stewart/Wrig Gainesville_AP_G Greensboro_GA
Homerville_AP Hunter_(AAF) Jesup_AP La_Grange
Lakeland Lawrenceville_AP Macon_AP Marietta
Marietta/Cobb Milledgeville_AP Moultrie_Muni_AP Newnan-Newnan_C
Peachtree_City Rome_GA Savannah Statesboro_GA
Swainsboro_AP Sylvania_AP_GA Thomaston_AP Thomasville_AP
Thomson_GA Tifton_AP Valdosta Valdosta/Moody
Vidalia Warner_Robins_A Washington_GA Washington_GA
Waycross_AP Winder_AP

Kentucky KY Temp Outlook

10-DAY DETAILED HOURLY WEATHER FORECASTS

Bowling_Green Covington Danville-Powell_ Fort_Campbell
Fort_Knox/Godma Frankfort_AP Glasgow_KY Henderson_City
Jackson_KY Lexington_KY London_Corbin Louisville_AP
Louisville/Bowm Middlesboro_AP Monticello_KY_AP Murray_AP
Owensboro_AP Paducah Richmond_Madison Somerset(AWOS)

Questions from the field this weekend

1. Granville/Person County

Dr. Poling,

I am the new horticulture agent for Granville and Person counties, and I had a call from a strawberry grower this morning, about whether or not to put his row cover on strawberry plants that lost their blooms this week due to the cold temperatures. Is there any benefit to having the covers on to encourage new blooms or is he better off leaving them off for sunlight purposes? I know if he still has blooms uncovered would be better for pollination purposes, but I did not know if he would benefit from increased temps by leaving them on.

Thank You,
Johnny

The main concern with plants that lost blossoms last week is to try to get these plants cleaned up! A number of  growers who lost a lot of blossoms last week are going ahead and “cleaning up” these plants now (removing the dead blossoms), and then probably applying captan. As far as leaving covers on to stimulate new blooms, I am not optimistic this will work. I actually ran a small study of this idea of using row covers in early March to try to add some new blooms at the Piedmont Research Station in Salisbury, and we did not see a  benefit compared to the non-covered plots (variety was  Camarosa). In the end, these are short day plants, and though there may be an opportunity to add blooms with row cover applications when the days are getting shorter in November (and, this is being done);  I believe our days are getting too long in the month of March.