Development of mechanized
application methods for applying
“Pheromone Rope” early season in cotton
By Mike Whitlow, ACRPC Field
Program Coordinator
The
necessity to explore all possible means of timely applications of ShinEtsu’s controlled release pheromone (PBW-rope) to non-Bt
cotton in a statewide eradication program led program managers to discuss the
feasibility of mechanizing this part of the program protocol.
The
application of “PBW-rope” has always been labor-intensive operations requiring
a labor crew to physically hand tie the rope to plants. In an eradication program, it is necessary to
apply the rope before the plants pin square (at approximately the 7-leaf
stage). This will assure that Pink
bollworm males are unable to successfully find females within the field, mate,
and subsequently the females laying eggs on hostable developing cotton squares.
The
anticipation of large acreage of non-Bt cotton, and a relatively narrow window
of application where the plants are large enough to tie ropes on yet prior to
pin square, presented a significant challenge to find and employ enough field
labor to accomplish the task. The rope
is applied at 200 per acre on a grid of 217.8 square feet. This equates to an application technique of
ropes being tied every 4th row and linearly every 16 to 17 feet.
The
pheromone is a controlled release from the reservoir within the rope, and
becomes an air-born scent carried by air currents. There are 200 release points per acre which
inundates the field with pheromone.
Adjustments may be made in either the width (number of rows) or the
length (linear placement down the row) and still achieve the desired number of
ropes per acre.
In
order to mechanize the application, it would be necessary to find some other
form of delivery to the field other than tying the rope to the plants. Small bamboo splints were a common product
found in nursery and floral supply stores which, when the rope was attached,
could then be applied in the seed line by hand or possibly mechanized. This method of application would also widen
the window of application by allowing rope to be applied earlier before the
plant was large enough to hand tie.
Rope,
when properly applied, had never presented a problem from cultivation or other
field operations of being inadvertently removed from the plant, and there was
no evidence that the picking operations could result in contamination at the
gin. In July of 2002, a field trial of
ropes, hand wrapped on nursery sticks, was applied to a field in the seed line,
followed by cultivation and subsequent field operations. In December of 2002, a field trial was
conducted on a variety of methods of applying rope (i.e. had tied loose,
twisted, on sticks, etc.) just ahead of picking operations. It was determined that pheromone rope wrapped
on sticks and applied in the seed line presented no threat to contamination at
the gin, and that normal field operations such as close cultivation would not
remove or effect the placement of the sticks.
The
next challenge was to find a method to efficiently wrap the pheromone rope on
sticks and develop a mechanical device to apply the sticks in the field. USDA-APHIS assisted in developing a prototype
wrapping machine, and a pneumatic driver that could be mounted on a tractor to
place the stick in the field. However,
testing of the wrapping machine eventually proved to discover that the rope was
wrapped too tight, resulting in the breakage of the rope matrix and the rapid
loss of pheromone as well as excessive cost to commercially develop enough
machines to effectively provide an estimated three million wrapped sticks. The application machine also seemed cost
prohibitive to develop and commercially be available and reliable in field
conditions. The conclusion drawn was
that we would need equipment that was already available on the market which
could be modified for our purposes.
As
a result, in February of 2004, the Council authorized the purchase of a single
transplanter and tool bar designed for transplanting seedling melon plants over
the top of plastic mulch. This equipment
allowed for the unit to travel down the row without making a furrow while
effecting the placement of the transplant using a “cup” or “shoe” that rotates
on a ground driven wheel punching a placement hole through the plastic mulch
and seed bed, then opening and depositing the transplant. Press wheels then firm up the soil around the
transplant.
Modifications
of the equipment for our purposes included:
1.
Removal of existing ground drive mechanisms that were designed to space melon
plants only inches apart (ropes would be placed in linear feet down a row).
2.
A hydraulic driven “orbit” motor installed to provide rotation of the
transplanter wheel, coupled to an electric actuated “clutch-brake” (designed
for assembly-line industrial applications).
3.
The 12-volt signal required to activate the rotation of the transplanter was
supplied via a sensor counting teeth on a sprocket mounted on a gauge
wheel. This is relayed to an adjustable counter
box that can be set to send the electrical signal on a pre-set count.
The
modified single unit transplanter was successfully demonstrated in May of 2004,
capable of placing a single pheromone wrapped stick in the cottonseed line at a
pre-determined distance down the row.
July
of 2005, the Council was ready to demonstrate two transplanters mounted on a
single tool bar allowing for the application of two rows in a single pass, six
rows apart. Additional design was needed
to strengthen the toolbars and larger press wheels were added for better
flotation in soft ground.
The
Pink Bollworm Eradication Program began in
The
equipment was repaired and serviced in the winter months and returned to
service in year two of the program treating another 3,000 acres of the non-Bt
planted cotton. Replacement of the
aluminum “shoes” or “cups” was required in the fall of 2007 because of
wear.
Each
unit requires a tractor driver and two “feeders” that are seated over the
transplanters which “feed” a pheromone wrapped stick into the cup after each
rotation. The tractor travels at 2 ½
mph. Linear placement occurs every
eleven feet of row every three seconds.
Depending on field size and distance of travel to additional fields, the
three units can easily complete 160 – 200 acres a day.
These
modified transplanters have provided an economical and accurate alternative or
supplement to field labor forces.
This page was modified
January 2008