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Strawberry Plasticulture – September 9,
2003 (Tuesday)
Vol 4, No. 45 (No.1)
In this advisory:
-1. You need a positive diagnosis!
-2. Setting the fresh dugs plants and irrigation
You need a positive diagnosis! In the current “plug crisis” it
is very important to get your problem plants properly diagnosed by
a qualified diagnostician, who will incubate infected tissue for 24
hrs and then observe for characteristic anthracnose spores and fungal
structures such as sterile setae. If a grower or propagator has “hotspots” in
his or her plug trays, contact your local Cooperative Extension Agent
and in North Carolina send samples to the NCSU Plant Disease and Insect
Clinic according to the clinic instructions:
http://www.ces.ncsu.edu/depts/ent/clinic/Submit/submit.htm
The advisories being provided on BerryAgent are intended to
help you recognize “field symptoms” for anthracnose, but
these photos do not constitute a positive diagnosis! In the rush of
events it is
easy for growers and agents to lose sight of the importance of having
this important documentation. Try to attend to this right away!
Figure 1. Dr. Frank Louws assisting Rick Icenhower, Icenhower Farms,
in taking a problem tray of Chandler plugs back to the Plant Disease
and Insect Clinic on Friday last week. Rick is in also in a difficult
situation as he is mainly a propagator of strawberry plugs and does
not grow strawberries. Replacing diseased plugs with fresh dugs does
not help his particular situation.
-2. Setting the fresh dugs plants. Perhaps the main objection of strawberry
plug plant growers to using fresh dugs relates to the significant amount
of hand labor required to set an acre of fresh bare-root plants. The
freshly dug strawberry plant is manually transplanted through the plastic
mulch in 2 _ inch slits cut by a specially constructed spacing wheel
(described in http://intra.ces.ncsu.edu/depts/hort/berrydoc/sept3_03/index.htm).
-2a. Cutting holes: I don't recommend punching holes any further in
advance than 2 days - the soil in the planting holes can easily dry
out in warm weather. Ideally, you would cut planting holes the day
you transplant (Fig. 2)
Figure 2. Cutting the holes for planting the day of planting (October
1, 2002).
-2b. Number of workers: We generally try to have on hand at least 10-12
workers for transplanting one acre of freshly dug strawberries (it
works out to about 40 hours of actual labor per acre). The idea is
to plant about _ to 1/3 rd of an acre and then get the overhead running
on that section. It is good to have 1 plant dropper for each 2 planters.
In Figure 3 (below) David Dycus (standing), Regional Agronomist, is
assisting with the dropping operation, and there is one planter working
with him. Once things “get working right” you will find
that 1 dropper can keep to 2 planters pretty busy.
Figure 3. David Dycus, Regional Agronomist, assisting with the dropping
operation at the farm of John Gross in October 2002.
Importance of firm bed When irrigation is started to establish plants,
any depressions in the bed can fill and bury the plant crown or the
ridge may erode and expose the roots. A firm plant bed will
assist in preventing the bed from settling or eroding (Figs. 4 & 5).
Fig. 4. At this location in Leicester, NC, the grower was able to pull
some excellent beds that are very firm (we stood on top of them last
Friday) and firm beds are one of the best ways to prevent problems
in plant settling. A heavy rain came soon after these beds were made.
Fig. 5. Another firm bed that was made this past weekend in Ramseur,
NC, on some real “red clay” – the grower worked over
the winter with a local equipment dealer to improve his bed making
technique to achieve this outcome.
Figure. 6. A full irrigation pond
needed for overhead sprinkling of fresh dugs.
-2c. Irrigation: Typically, it is important to plan on at least 7 days
of CONTINUOUS overhead watering (in some years it is necessary to have
up to 10-12 days). Start the irrigation each morning when the plants
show the first signs of wilting and continue to irrigate (1/10th inch
per hour) until the hot part of the day has passed. After several days,
irrigation can be initiated later in the morning and can be discontinued
earlier in the afternoon. This is not irrigation for drought control – this
type of irrigation is essentially for orative cooling purposes. The
purpose of this type of irrigation is to prevent foliage loss until
the root system can get established again. The goal: you must make
sure that plants have 3 or more fully green leaves (original) remaining
at the end of the establishment period (Figure 7).
Fig. 7. Freshly dug transplants should have three or more healthy
original leaves remaining at the end of the establishment period. Note
the development of two new leaves from the crown 3 weeks after transplanting.
Fig. 8. Overhead sprinkling of fresh dugs must start within 30-45
minutes after planting to achieve optimum establishment (survival of
3 original leaves – see Fig. 7).
Irrigation on the day of planting – INITIATE OVERHEAD SPRINKLING
AS SOON AS PLANTS ARE SET – NO MORE THAN 1 HOUR SHOULD ELAPSE.
SUCCESSFUL RESULTS HAVE BEEN ACHIEVED USING 1/10 INCH PER HOUR. Warm
and windy days make it VITAL to start within 30 - 45 minutes of setting
plants in each _ to 1/3 acre section. You may wish to even install
cut-off valves in individual sprinklers (something being done by John
Gross in Sanford ( jtgross@alltel.net). Once you start running water,
keep pumping until sundown the first day. Normally growers are advised
to turn on each morning at the same time (usually 9 am), but you can
observe the plants for the first sign of moderate wilting and turn
on then. We have conservatively calculated the water requirement for
a 9am-5 pm daily schedule for 7 days as follows (based on 1/10th inch/hr
precipitation rate):
7 days at 1/10th inch/hour for 9 am – 5 pm
Daily – 8 hours/day x 1/10th inch = 8/10ths inch, or 21,723 gallons/day
(one acre inch = 27154 gallons)
7 days x 21,723 = 152,061 gallons
(one acre foot = 325,850 gallons)
If the grower has 4 acres:
Daily – 4 acres x 21,723 gallons/A = 86,892 gallons
Weekly – 608,244 gallons
Here is a brief listing of irrigation dealers to assist you in developing
an optimum configuration for your sprinkler irrigation system ( I am
pleased to list other dealers – just send an email to: barclay_poling@ncsu.edu):
Joe Davidson, Berry Hill Irrigation, 3744 Hwy 58, Buffalo Jct., VA
24529, 800-345-3747 usedrip@kerrlake.com, www.berryhilldrip.com
Leon Fulmer, W.P. Law Inc., 303 Riverchase Way, Lexington, SC 29127,
804-461-0599, fulmer@wplawinc.com. www.planinc.com
Henry Johnson, Johnson and Company, PO Box 122, Advance, NC 27006,
800-222-2691 336-998-5621, hjirr@aol.com
-2d. Planting technique: In addition to getting a line on a
dozen or more workers for planting, you need to consider the experience
level
and language of the work crew you will be using for setting fresh dugs.
For the purpose of this advisory I will assume that the workers have
no experience in setting fresh dugs (The NCCES is also working on a
2 page step-by-step guide in Spanish for workers who do not speak English – we
hope to have this posted to BerryAgent by the end of this
week).
Planting-depth Set the plants so that the midpoint of the crown is
level with the soil surface (Fig. 9). If plants are set too deep, the
plants are unthrifty and crowns rot and plants die. If planted too
shallow, the root system is exposed, which can result in poor rooting
and shifting of plants. Often plants may be set at the right depth
but either be in a small depression or have soil ridged around the
crown. When irrigation is initiated to establish plants, the depression
can fill and bury the crown or the ridge may erode and expose the roots.
Fig. 9. Set the fresh dug plant so that the midpoint of the crown is
level with the soil surface. It is very important not cover with soil
the terminal growing point (the relatively small terminal growing point
is just above my index finger and is tucked in between the 4 leaf petioles
shown here).
Fig. 10. Diagrammatic of strawberry plant and terminal growing point
(note the location of the center rowing point relative to the base
of the leaf petiole). Never allow workers to set fresh dugs so deeply
that this terminal is covered with soil.
The roots must also not be "j-rooted" when set in the hole.
This has been a very serious problem with inexperienced planting crews.
One of the best ways to avoid this situation is to trim or prune the
roots ahead of transplanting and shorten to 5-6 inches (Fig. 11).
Fig. 11. Roots are to be trimmed before planting to about 5 inches
from the base of the crown (some will be 4 inches and others as much
as 6 inches as the crowns in the bundles are not lined up, and it is
not necessary to do so).
Fig. 12. Carefully “sliding” the
fresh dug plant roots straight down into the soil. This tool is ideal
for sandy and clay-loam type soils but is not advised for harder clay
soils.
Fig. 13. The plant is almost deep enough (see Fig. 14).
Fig. 14. After setting the plant to this depth it is a good suggestion to tell
workers to hold the base of the plant as the other hand slides the tool out
- this keeps the crown at the right depth. You really only need to turn the
water on at this point – the extra packing shown in Fig. 15 is not really
not that critical.
Fig. 15. This worker is using his fingers to pack some additional
soil against the base of the fresh dug to help it stand semi-erect
after setting. However, this is not a critical practice – the
main issues are: 1) correct planting depth, 2) setting the roots vertically
into the planting hole (no j-rooting), and 3) making sure that the
entire root system is now in intimate contact with the soil after setting.
Irrigation helps to fill in small air pockets around the roots. Also,
workers must be extra cautious to not snap or break the leaf petioles
(see the broken petiole in Fig. 16).
.
Fig. 16. It is typical for the fresh dugs to “lay down” just
after setting. Do not expect fresh dugs to stand erect just after planting – they
do not usually start coming up until the next day (following continuous
irrigation on the first day).
Fig. 17. On a sunny warm day it is advisable to start sprinkling within
30-45 minutes of planting – this field has been zoned off to
allow the completion of 1/3 acre sections before irrigating (in this
case the grower pushed it a bit and this water until nearly 1 hour
after transplanting – notice how flat the plants are in the bottom
right of the photo).
Fig. 18. Check with your irrigation dealer immediately if you are
not set up to apply 1/10th inch/hour sprinkling rate. Many growers
have systems designed higher application rates needed for more severe
frost/freeze episodes. Higher application rates than 1/10th inch are
wasteful and cause more soil washing. Big guns are not recommended.
Fig. 19. Photo of the same fresh dug plants shown in previous figures
during the third week in May 2003. The grower was very pleased with
this Chandler crop and the fact that he had a much lower plant bill
compared to plugs!
E. Barclay Poling, Small Fruit Specialist
Campus Box 7609
Kilgore Hall - Office 252
NC State University
Raleigh, North Carolina 27695-7609
919.515.1195
919.515.2505 (fax)
919.418.9687 (mobile)
web site:
http://intra.ces.ncsu.edu/depts/hort/berrydoc/
click HERE
to return to strawberry advisories page
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