VegNet Vol. 12,
No. 10.
On the WEB at: http://vegnet.osu.edu
If experiencing problems receiving this
fax, Call 614-292-3857
In This Issue
1. Aster Yellows is
Here!
2. Weed Control in Cucurbits
3. Why You Should Complete
Prevailing Wage Surveys
4. Crop Reports
5. So Just How Clean Is Your Water
Aster
Yellows is Here! By Sally Miller and
Casey Hoy
Aster yellows is a serious disease of
lettuce, celery, carrots and other vegetable crops in
2005
The numbers of leafhoppers observed and percentage infected are
high enough to result in serious aster yellows problems. Leafhopper
control in susceptible crops, especially lettuce, over the next few weeks will
be crucial in minimizing the epidemic over the remainder of the growing
season. The two most important times to control the leafhoppers are
approximately 7-14 days after transplanting or emergence and approximately
21-14 days before harvest. The first timing is to protect the current
field from infection by incoming adult leafhoppers, and should be a material
with long residual activity. The second timing is to prevent any
leafhoppers that have developed in the field from moving the disease to other
fields, and should be a material that provides thorough and rapid control of
nymphs. A distance of at least 60 yards between susceptible fields, and
especially moving plantings for the next few weeks as far as possible from
current plantings, can also reduce the movement of leafhoppers between fields
and reduce the disease.
Weed
Control in Cucurbits by Doug Doohan
With the heat and good soil moisture in many areas of the state,
seeded crops are more than cracking; they are bursting out of the ground and
growers are getting caught without pre-emergence (PRE) weed control in place.
In cucurbits this can be a critical concern because of the very few
post-emergence (POST) products available. If cucurbits are seeded but not
emerged Sandea, Strategy, Curbit
and Command 3ME are all legitimate choices. PRE products such as Dual Magnum and Outlook are not yet registered on
cucurbit crops. Sandea PRE is probably the most
effective way to go after heavy lambsquarter
populations. Both a PRE and a POST Sandea can be
applied to most cucurbit crops. If two applications of Sandea are likely, don't exceed 1/2 oz/A per application. A non-ionic surfactant (
Generally Sandea should not be applied
from ground-crack until at least the 2 true leaf stage of the crop. POST Sandea applications applied too early ( ie before 2 true leaves) may cause severe chlorosis from which the crop will only slowly
recover. If cucurbits have cracked or emerged before PRE sprays were
applied, cultivate immediately to kill white-thread stage or emerged seedlings
(or spray a non-selective herbicide with a shielded sprayer). Chances are
with the heat the crop will move from ground crack to the 2 true leaf stage quickly
and POST treatments can be safely applied. Remember that Sandea POST controls a wide range of broadleaf weeds but
does not control emerged lambsquarters. POST
applications targeted at pigweeds, ragweed and morning glories (not labelled but sensitive at the very early seedling stage)
will prevent further emergence of lambsquarters for
several weeks.
Why You Should Complete Prevailing Wage Surveys
By John Wargowsky, Executive Director, Mid
American Ag and Hort Services
I consistently hear Ohio employers of seasonal and migrant workers
express concern about the availability of legal and willing workers in
agricultural activities such as nursery, sod, fruit, vegetables and livestock.
One program that increases
To facilitate this program, the Foreign Labor Certification Unit of the Ohio
Department of Job and Family Services (ODJFS) is required to conduct Prevailing
Wage Surveys. The information collected from these surveys assures that the
foreign H-2A temporary workers and domestic workers receive the same pay. This
assures no domestic workers, including permanent residents and U.S citizens,
are being adversely affected by the program.
All individual survey information is protected by the Federal Privacy Act and
only collective information is published. This information is published on-line
at http://workforcesecurity.doleta.gov/foreign/aowl.asp.
The bottom line is that I encourage employers receiving such surveys from ODJFS
to take the time to accurately complete and return the surveys. This process
improves the employment capacity for
Crop
Reports
Weather is foremost on the minds of local vegetable growers.
Sunny, summer weather has arrived, 9 days over
90 degree temperatures and overnight temperatures above 65 degrees Fahrenheit.
Perfect tomato growing weather and the plants have responded with leaf &
stem growth and setting of tomatoes. Some growers are concerned that dew
is not drying up on the leaves until almost
Finishing suckering of later planted
tomatoes. Trellising tomatoes. Peppers are
beginning to set fruit. Vine crops are beginning to run and soon
should be in flower.
Insect trap count: No European Corn Borer
or Corn Earworm have been trapped in helio traps
through Tuesday June 14th. Have spotted no European Corn
Borer damage in corn tassles or leaf
whirls. No Beet Army Worm moths have trapped through June 14th.
Pumpkins: Have noticed heavy cucumber beetle activity on young
pumpkins. There has been a need to spray. Pumpkins seem to be doing
well....Pumpkins planted during the first week in June germinated quickly and
are growing rapidly.
Got some needed rain this week.
Sweet corn - Growing well with the warm
weather that we have had the past two weeks. Got
some needed rain this week.
Reports of green beans having to be replanted......leaves growing
slowly.
European
corn borer moths were easily seen while walking fields on Monday (6/13).
However, the number of corn plants infested with larvae remains low
(1-2%). Several fields of onions had to be sprayed last week for thrips. Two spotted spider mites are showing up at
threshold levels in strawberries and eggplant. We expect to find them
soon in vine crops. Cabbage fields are going over threshold for diamond
back moth larvae and imported cabbage worm. Flea beetles are also going
over threshold in cabbage, potatoes and eggplants. The aphid population
seems to have leveled off for right now with few fields going over threshold
this past week. This may be due in part to the many beneficial insects we
are finding in the fields. Bean leaf beetle populations seem to be going
down as well. We still have more sweet corn to be planted and tomato, pepper
and melon transplants to go into the ground.
So, Just
How Clean is Your Water? June
2005 by
As we work through another year of helping growers with the
application of Good Agricultural Practices (GAPs) to
their fresh produce operations, I am repeatedly reminded of just how important,
and potentially confusing, is the issue of water quality. First of all, we
emphasize in our education programs that water quality is one of the most
critical control points for minimizing the risk of foodborne
illness. Of course, water contamination of any kind: chemical or
microbiological is to be avoided both out in the field and in the packing
house. In the GAPs program we provide recommendations
based on good, general science yet, we emphasize that no standards have been
established for fresh produce. Ultimately we end up applying the standards for
potable water and wait for the research to tell us if we have any other options
or considerations.
I have written before about the standards for water testing and treatment of
wells and will repeat just a few words about it here. Anyone who has heard me speak, has heard about testing wells annually and open water
sources quarterly for fecal coliform and E. coli.
During farm consultations we provide Standard Operating Procedures (SOPs) that
give growers methods for solving a contamination problem whether it’s for water
intended for use out in the field, or for water used in the packing house.
Those SOPs generally rely heavily on the use of chlorine (in its variety of forms)
to treat the water, killing bacteria present in the water and, depending on the
level of free chlorine in the water, killing some bacteria on the surface of
produce being washed.
And yet the world is a changing place, new problems pop up, and, if we are
lucky, new solutions present themselves as well. Some growers are using
sanitizers other than chlorine to solve a number of problems inherent to using
chlorine (fumes, corrosion, discharge issues, to name
a few). Some of the methods I have seen more commonly employed in the
Copper Ionization is an electrical method that generates electrically charged
copper ions into a water system. These ions are reactive and are thereby
capable of inactivating bacteria, mold, mildew and similar microorganisms. The
level of copper used by these automatic systems is not toxic and copper has
been effectively used to generally control disease in other applications. The
effectiveness of copper ionization on certain spore-forming bacteria and
parasites is questionable when it is not monitored or controlled properly. All
systems should have a method for being able to monitor the copper ion level in
the water. Combination with another sanitizer (i.e. chlorine, hydrogen
peroxide, etc.) is a way to cover all of your bases, yet maintaining lower
levels of reactive oxidizing sanitizers.
Using hydrogen peroxide or hydrogen dioxide is another acceptable method for
achieving water sanitation. Here, we are taking a form hydrogen and oxygen
molecules that are highly reactive, bringing them into contact with organic
material (bacteria), and (at a high enough level) effectively killing bacteria,
parasites and inactivating viruses. One big plus of using these compounds is
that the by-products of their reactions are water and oxygen. There is no need
to be concerned about fumes or water discharge; however, these are reactive
materials and should be handled carefully. Again, monitoring the level of the
reactive components is critical to maintaining control over your sanitizing
system.
Of course these are only two alternative sanitation methods for water treatment
of many. Regardless of the one you choose, the most common error I find is that
there is no monitoring system for the water sanitation system. With chlorine,
people are accustomed to using test strips to measure the free chlorine levels.
If they combine this measurement with monitoring the pH of the water, they can
be sure to maintain the right balance in the water to achieve inactivation of
microorganisms. A pH that is either too high or too low will result in the
chlorine moving into a form that will not be effective for killing
microorganisms. And if you simply dump and don’t measure, you may just be
throwing money down the drain.
Using an ORP system to monitor the effectiveness of your water treatment system
may be a more useful and easy method to assure that your treatment system is
working for you on a consistent basis. ORP stands for Oxidation-reduction potential.
An ORP system is a system that can measure the oxidation-reduction potential
(in terms of milli-volts (mV)) of the treated water.
Research has shown (Trevor V. Suslow, Ph.D., UCDavis, Pub. 8149, 2004) that a
reading of 650-700 mV will result in the killing of pathogenic bacteria within
30 seconds. Advantages of this system can be automated dosing based on system
readings, automatic recording of measurements (helpful for those who face
third-party audits), and reduction of the need to test the water for pH.
Maintaining backup methods with which to calibrate your ORP system is strongly
recommended. Ultimately you should know as much about your water chemistry (pH,
mV, free ion levels) as you probably know about the soil chemistry of your
fields. Failing to monitor is a failure to control. Water systems that are out
of control are at a much greater risk for being the source of a foodborne outbreak. Minimize your risk and measure.