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Strawberry Plasticulture April 5, 2003 (12:30 pm)
Vol. 4, No. 25 Brief Weekend Outlook
-1. Weather today:
It is going to be quite “warm” this afternoon (perhaps
mid-80s in the canopy at Clayton).
A couple of showers in the Mountains today. Highs in the piedmont expected
to be in 80s. A cold front will approach tomorrow with showers and
thunder (some inexpensive evaporative cooling!). Sunday will be partly
cloudy and breezy, and Monday April 7 expecting steady rain.
-1a. Daily evapotranspiration amounts of 0.24 yesterday and also on
Wed. were recorded at Clayton. So, we are planning to run some drip
irrigation using tensiometers to guide us (usually around 1 _ - 2 hrs
is our run time).
-1b. Evaporative cooling is usually not practiced until we get into
upper 80s and 90s in the canopy - last year we experienced a disaster
in mid-April where daytime temperatures in the 90s and 100s destroyed
a substantial amount of the crop for late season. Hopefully, temperatures
will stay in lower 80s today.
-2. Mites report by Dr. Ken Sorensen (11 am, April 5):
In checking plants at Castle Hayne this week, Dr. Sorensen found 50%
of the plants with 2-spotted spider mites present, and 3-5 adults per
leaf blade. This is well past the treatment threshold of 5%! Treatment
is somewhat tricky due to highly variable weather this weekend - rainfall
can complicate treatment. Dr. Roy Parker, Uniroyal, has indicated that
Acramite is rainfast in just 2 hours (phone call at noon to Roy). So,
if you have a population of mites that is beginning to build, it may
be well to treat very soon, despite the variable forecast for the weekend
through next Monday. In Wake Co., Dr. Sorensen did not see mites in
fields he visited in southern part of Wake. He attributes this to recent
freeze protections and field wetness. As Dr. Sorensen said, the mites
are “not aquatic”. Dr. Sorensen reminds us that with day
temps in the 80s and nights in the 50s, you can get substantial mite
buildup in 3-4 days. His preferred material for treatment of adults
in Acramite (as opposed to pyrethroids such as Brigade, which is very
broad specturm and kills beneficial insects and mites as well). At
this time of year we are very concerned with honey bees and the pyrethroids
are highly toxic. Acramite is very “kind” to populations
of beneficial/predaceous mites and insects (including honey bees).
-3 Fertility:
I have been checking tissue sample reports for a number of fields and
so far things are looking very good.
-2a. Boron - if you have not fed any boron yet this season and values
are getting low (based on tissue sample results), then it is important
to make this injection soon. Follow tissue report recommendations.
Never more than 1/8 lb (0.125 lb) boron/acre at a time. If using Solubor
(20% boron), this would be only 0.625 lb (10 oz) of product per acre
(calculation check: 0.625 lb x .20 = 0.125 lb boron "active").
-2b. Liquid N use: for the 30% Liquid N you only need to determine
the total lbs of N you wish to deliver, and divide by 3.25 to get the
number of gallons of this liquid fertilizer needed. For example, if
the grower needs to inject 10 lbs of N, then divide 10 by 3.25 = 3.07
gallons needed. This product contains 3.25 lb of actual N per gallon.
Alternatively, you may be starting out with 0.75 lb N/day and wish
to feed for one week: 7 days x .75 lb N/day = 5.25 lb N; 5.25 lbs of
N divided by 3.25 = 1.62 gallons (1 gal = 128 oz).
-2c. Ca levels: Calcium nitrate is an excellent N source to consider
if calcium levels in tissue samples are running low (0.50 0.60 %).
Frost for next week?
There is no indication of any frost/freeze for at least another week
or more I checked the AWIS forecast for all parts of NC and our coldest
areas in Mtns will see some upper 30’s early Sunday morning (Apr.
6). The mountains will see some upper 30s on Wed/Thur (early Thur morning).
Concern about skipping leaf sanitation and botrytis? Please continue
to follow the spray schedule during bloom for botrytis control and
the extra dead leaf tissue on the beds should not be a problem, according
to work in FL and NC.
Reminder: Strawberry Tour on April 8th (Milton Parker see yesterday’s
advisory, or call Milton today to register)
Milton B Parker
Phone: 910.640.6606
Fax: 910.642.6315
E-Mail: Milton_Parker@ncsu.edu
Have a great weekend!
Barclay Poling
Extension Specialist (Small Fruits)
NC State University
click HERE
to return to strawberry advisories page
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