Strawberry Plasticulture HEATWAVE ALERT - April 18, 2002 (10 am)
Vol. 3. No. 33, Dr. Barclay Poling, Strawberry Extension
Specialist
-1. Record heat wave continues - recommendations for today
-2. Grower questions on evaporative cooling
-3. Agent reports - Billy Little, Wilson Co., NC
-4. What's in store for Friday?
Record heat wave continues: The mercury is heading up again today
into the high 80's and even 90's in parts of ENC. We had a high temperature
in Raleigh of 91 F at the airport yesterday. However, a weak disturbance
arriving today will cause spotty thunderstorms in a number of areas. The
break in this heat will thankfuly come this weekend (Sat. high 82 F, and
Sun. high 74 F in Raleigh). Since I have been having some "laptop
problems" this week, I'd like to simply advise that if your area
is expected to go above 85 F today, and you don't have anthracnose, then
you may wish to consider evaporative cooling this afternoon.
Fig. 1. Maximum temperatures for Thursday, April 18, 2002
Fig. 2. Maximum temperatures for Southeast region, April 18, 2002
Here is the chart from SkyBit (our sincere thanks to SkyBit for the use
of this information).
RECOMMENDATIONS FOR THURSDAY
Evaporative Cooling on April 18, 2002 for areas > 85 F this afternoon, and no anthracnose present. Here is a suggested sprinkling schedule (low precipitation rates are recommended, 1/10 in./hr is adequate)
No. 1) 12:30 pm - 1 pm, and then shut down until 1:45 pm
No. 2) 1:45 - 2:15, and then shut down until 3:00 pm
No. 3) 3:00-3:30 pm, and let the crop dry before night
Because it should be slightly cooler than yesterday, you may only need 2 sprinklings today, not 3 (as shown above). Many farmers have said that their toughest temperatures come at around 2:30 - 3 pm. Growers who are not in the hottest areas of the state and region may wish to consider one sprinkling at around 2:30 pm today. I am concerned now that this 5 day heatwave is beginning to adversely affect the potential length of the season and maybe damaging some of the later blooms. Heat will always serve to shorten the strawberry harvest season. Remember, strawberries are a cool season crop, and we really need to get back into those pleasant mid-April temperatures in the 70's in order to achieve a full picking season.
Areas getting one of the afternoon T-storms may not have to do any evaporative cooling!
-2. Grower questions
(VA grower - 4/18/02)
1. Is sunscald a major problem with berries that
are not ripe yet?
Ans. Sunscald is mainly a problem on the
red-ripe berries - these are very subject to breakdown. It is less common
on the green fruit. If I did some cooling in your area today it would
be primarily for the purpose of season extension.
2. We didn't notice sunscald yesterday and it was
90.
Ans. This is not surprising - for the stage of crop development indicated
(green fruit).
3. Also, will our plants stop blooming at this
point if the heat continues, and not start back up if the temperatures
cool back down to normal 70's and 80's?
Ans. I am afraid that we are going to see detrimental effects of this
several day heat wave in terms of reduced season length and highly concentrated
ripening. This much heat (90 F) is tolerable if it lasts for a day or
two, but we may have 5 straight days of this! We really don't know a lot
about this evaporative cooling procedure. Not too many years ago I put
out an advisory in which I said not to do it, and luckily many growers
went ahead with it, and proved to my satisfaction that it really does
work for preventing losses of red-ripe fruit to sunscald. We can't report
as easily on how well this procedure may serve to prevent shortening of
the season. But, my "gut" is that it is worth doing, even with
a crop at your stage - that would be my recommendation to keep the plants
blooming for a longer period.
The ideal temperature situation is to have daytime in the 70s and low 80s in the second half of April, not high 80s and 90s. This is brutal! The strawberry is a "cool-season" crop, and these hot temperatures are going to reduce season length. Please send digital pictures (if you have one of these cameras) of any blooms that you feel may have been injured by the heat yesterday.
-4. Agents in the field yesterday and today -
Yesterday (April 17)
"Just wanted to drop a note for our area. Fruit production is very
heavy and picking good. Started picking the misshape and odd size end
of last week and fields are open this week. Today most everyone is doing
cooling in their fields. Insect and disease pressure are about as low
in all the
fields as I have seen. We do have some anthracnose but aware of it early
and he has been doing a good job of controlling it. That particular field
we are not going to overhead cool at the moment. We have stepped up the
drip irrigation in that field during this spell. Take care, Billy
--
Billy Little
Agricultural Extension Agent
NC State University
College of Agriculture and Life Sciences
North Carolina Cooperative Extension Service
Wilson County
1806 S Goldsboro Street
Wilson, NC 27893
email: Billy_Little@ncsu.edu
voice: 252-237-0111
fax: 252-237-0114
Today (April 18)
Billy,
Once again, let me thank you for this report from the berry patches of Wilson County! My travel is presently quite limited and this information is even more helpful than you realize.
I think our readership will appreciate the modifications your growers in Wilson Co. made on the evaporative cooling schedule I suggested.
Let me recap it for everyone below (Wilson Co., NC - high in Wilson of 86 F, according to AWIS, but at the strawberry canopy, and especially for ripe berries in contact with black plastic and exposed to the sun, the fruit pulp temperatures are much much higher). I note that your growers prefer the 15 minute cycle to 30 minutes being used by several growers in VA yesterday. I really need to see some of the results of doing this for 15 vs 30 vs 45 minutes!!
No. 1) 1:15 - 1:30 pm, and then shut down for one hour
No. 2) 2:30 - 2:45 pm , last irrigation of day
Thanks,Barclay
-4. What's in store for Friday? I am afraid the news is not good!
At Clayton Central Crops we are expecting 96 F in the canopy tomorrow.
This is a definite "Evaporative Cooling" opportunity. That kind
of temperature will scald ripe berries and even some of the white/pink
stage are possibly vulnerable. Moreover, there is the effect of these
scorching temperatures on remaining open blossoms. We've never seen anything
quite like this before so early in the season!
Fig. 3. NC maximum temp map for Friday (April 19, 2002)
Fig. 4. Southeast maximum temp map for Friday (April 19, 2002)
Thanks for all the feedback from yesterday's advisory...
E. Barclay Poling, Small Fruit Specialist
Campus Box 7609
Kilgore Hall - Office 252
NC State University
Raleigh, North Carolina 27695-7609
919.418.9687 (mobile)
barclay_poling@ncsu.edu
|
advisories
| events
| berrybeat
q&a | agent
info | proceedings
| weather
| pest
info|special
reports | regional
experts |
all
material © Barclay Poling
site designed and maintained by: LiquidSun
d e s i g n
