Introduction
Several species of
vines grow on oil palm stems and their presence makes it difficult to
judge bunch ripeness during regular harvesting cycles. Many of these
plants belong to the Araceae family (Philodendron sp., Syngonium
podophyllum), which are able to climb the stem from the weeded circle
around the palm when weed control is inefficient.
Normally, these vines are removed manually, but during the operation,
many fragments drop to the ground and will root if not removed, making
costs even higher. Some systemic herbicides offer a good alternative for
handling this problem, but special precautions must be taken to avoid
drift and worker contact with the chemicals.
During a preliminary trial, two mixtures showed promise: (1) One part
water, one part WK® (adherent), and one part glyphosate; and (2) One
part water, one part WK, and a combination of three parts glyphosate to
one part triclopyr. When triclorpyr was used in a higher proportion, it
caused rapid defoliation, but the stems of the weed remained alive and
hanging around the palm stem.
This paper details the results of a trial that had as its main
objective the optimization of glyphosate and triclopyr mixture, and the
application method, in order to obtain the best control of Philodendron
sp. growing on oil palm stems.
Materials and methods
The experimental units were oil palm stems with at least 60% coverage
of Philodendron sp.
(Fig. 1).
Treatments are described in Table 1. Herbicide blends were applied
with a paint roller, equipped with a brush meant to be used on a regular
smooth wall (Fig. 2). This equipment avoids drift and also eliminates
drips that could affect the workers. Each palm stem got approximately
100 ml of the mixture. During the application period, mean temperature
and relative humidity were 32ºC and 82%.
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Table 1. Herbicide mixtures used in a trial
to control the vine Philodendrom sp. growing on oil
palm stems
| Treatment |
Proportions |
| Water |
WK® |
Herbicide |
| Glyphosate |
Triclopir |
| 1 |
1.25 |
1 |
0.75 |
0 |
| 2 |
0.375 |
0.375 |
| 3 |
0 |
0.75 |
| 4 |
1.50 |
1 |
0.50 |
0 |
| 5 |
0.25 |
0.25 |
| 6 |
0 |
0.5 |
| 7 |
1 |
1 |
1 |
0 |
| 8 |
0.75 |
0.25 |
| 9 |
1 |
0 |
| 10 |
0.75 |
0.25 |
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7 and 8 were control treatment based on previous trials.
* Treatments with WK® were substituted by a surfactant derived from
palm oil (Agrofilm)®
WK = adherent-surfactant
Amonium sulphate (20 g/l) was used in all treatment to improve the
herbicide effect. |
The effectiveness of the commercial coadjuvant WK® was compared with
a product derived from palm oil (Agrofilm®). The degree of control was
determined at 22, 45 and 65 days after treatments were applied.
Statistical analysis was done using ANAWIN 2005, using a completely
randomized design, with 10 treatments and five replications. Means were
compared using a MSD test (p = 0.05). Treatment effectiveness was
checked 10 and 20 days later, using the scale in Table 2.
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Table 2. Scale for evaluating the degree of
control obtained with several herbicide mixtures applied to
Phylodendron sp. creeping on oil palm stems
| % of control |
Degree of control |
Symptoms on plant |
| <10 |
Poor |
No apparent effect |
| 11-20 |
Light |
Atrophy and/or light chlorosis |
| 21-30 |
Moderate |
Light atrophy, light chlorosis and light
necrosis |
| 31-40 |
Medium atrophy, severe chlorosis, and light
necrosis |
| 41-50 |
Medium atrophy, severe chlorosis, light necrosis
and some plants dead |
| 51-60 |
Good |
Severe atrophy and/or increase in the number of
dead plants |
| 61-70 |
Between 61 and 70% of plants dead |
| 71-80 |
Between 71 and 80% of plants dead |
| 81-90 |
Between 81 and 90% of plants dead |
| >91 |
Excellent |
Between 91 and 100% of plants dead |
The trial was conducted during the months of March and May, 2005
(523.3 mm rainfall), in a commercial oil palm plantation located on the
central Pacific coast of Costa Rica (9° 23,442´ N; 84° 03,631´ W).
Results
An oil palm stem, with a mean coverage of 60% of Philodendron sp. can
be treated with herbicide in less than four minutes (average 3.36 min),
which compares very favorably with the time needed to do this job
manually (approximately 25 minutes), which does not consider the extra
time needed to collect the plant fragments that drop to the ground or
onto leaf axils. The chemical treatment results in a time economy of 87%
in labor, and highly reduces the risk that any plant fragment will
sprout again (Fig. 3 and
Fig. 4). All treatments gave an adequate level of
control during the first 65 days according to scale in Table 2.
The coadjuvant Agrofilm, which is obtained from palm oil, was
superior to WK and was less expensive (61%). In general, the chemical
treatment was less expensive than the manual one (36% less costly per
palm). The best treatment was the mixture of one part water, one part
Agrofilm and one part glyphosate, which cost 64% less than manual vine
removal (Fig. 5,
Fig. 6).
Conclusions
It is possible to have efficient and economic control of creeping
plants of the Araceae family growing on oil palm stems. When these vines
grow vigorously on the palm stem, they negatively affect harvesting,
because they interfere with the workers' ability to correctly judge
bunch ripeness. Philodendron sp. can be readily controlled using
glyphosate applied with a paint roller, which eliminates drift and
avoids chemical contact with workers.
The use of other herbicides mixed with glyphosate did not improve its
performance, but a coadjuvant obtained from palm oil (Agrofilm), greatly
improved control and was not as expensive as other commercially
available products. Agrofilm can be substituted with refined oil palm
olein plus 1.5% v/v of an emulsifier.
It is possible to use a knapsack sprayer to apply the herbicide and
increase efficiency. However, special care must be taken to avoid drift,
and not to apply the product on inflorescences and bunches.
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