Effect of Tree-Crop Combination on the Pest and Disease Occurrence in Bush Bean (Phaseolus vulgaris Linn.)
BIBLIOGRAPHY
SHRESTHA, RAJU. APRIL 2009. Effect of Tree-Crop Combination on the
Pest and Disease Occurrence in Bush Bean (
Phaseolus vulgaris Linn.). Benguet State
University, La Trinidad, Benguet.
Adviser: For. Jimmy A. Wakat , BSF
ABSTRACT
The study was conducted to compare the disease and pest incidence on the bush
bean grown conventionally and bush bean grown with trees and non-crop plant species.
Bush bean grown in conventional method was significantly infected by disease
and pests while the plants grown with tree and non-crop plants showed a low degree of
disease and pest incidence. One of the highly contrasting results was that the Fusarium
wilt disease incidence in the conventional method was 62% while in the tree-crop
combination there not even a single incidence. There was also a significant difference in
bean rust, leaf curling, leaf miner, and pod borer incidence.
Significantly higher less non-marketable yield was noted in the tree-crop
combination. As a consequence, the Return on Investment (ROI) was much higher in the
tree-crop combination.
TABLE OF CONTENTS
Page
Bibliography .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
REVIEW OF LITERATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
MATERIALS AND METHOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
RESULTS AND DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
Disease Incidence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Pest Incidence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Soil Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Yield and Yield Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Return on Investment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Trees (Woody) and Non-woody Plant Species . . . . . . . . . . . . . . . . . 25
Inventory of Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
SUMMARY, CONCLUSION AND RECOMMENDATIONS . . . . . . . . . 35
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
ii
INTRODUCTION
Today almost all vegetables and crops are grown with the help of chemicals and
are protected with pesticides. As a consequence, the consumers have no options but to
consume those highly pesticide-contaminated products. The results of numerous
researches related to the effect of pesticides and chemicals have already proved to be
negative to the human health and environment. It creates pest control problem through
resistance development, and by killing natural enemies of pests.
Economically, in agriculture particularly in monoculture, the burdens include the
need to supply crops with costly external inputs; since agroecosystems deprived of basic
regulating, functional components lack the capacity to sponsor their own soil fertility and
pest regulation. Often the costs involve a reduction in the quality of life due to decreased
soil, water, and food quality when pesticide and/or nitrate contamination occurs.
Agriculture implies the simplification of biodiversity and reaches an extreme form
particularly in monocultures. The result is the production of an artificial ecosystem
requiring constant human intervention. In most cases, this intervention is in the form of
agrochemical inputs, which, in addition to boosting yields, result in a number of
undesirable environmental and social costs (Altieri, 1994).
Nowhere are the consequences of biodiversity reduction more evident than in the
realm of agricultural pest management. As agricultural modernization progresses,
ecological principles are continuously ignored or overridden. Hence, modern
agroecosystems are unstable and breakdowns manifest themselves as recurrent pest
outbreaks in many cropping systems and in the form of salinization, soil erosion,
pollution of water systems, etc. The worsening of most pest problems has been
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
2
experimentally linked to the expansion of crop monocultures at the expense of vegetation
diversity, which more often than not, provides key ecological services to ensure crop
protection (Altieri and Letourneau, 1982 as cited by Altieri, 1994).
In modern agroecosystem, the experimental evidence suggests that biodiversity
can be used for improved pest management (Andow, 1991 as cited by Altieri, 1994).
According to these theories, a reduced insect pest incidence in polycultures may be the
result of increased predator and parasitoid abundance and efficiency, decreased
colonization and reproduction of pests, chemical repellency, masking and/or feeding
inhibition from non-host plants, prevention of pest movement or immigration, and
optimum synchrony between pests and natural enemies.
This study focuses particularly on the ways in which biodiversity can contribute
to the design of pest-stable agroecosystem. The reason for choosing bush bean
(
Phaseolus vulgaris Linn.) as a main crop is, it is one of the most popular vegetable
grown commercially by Benguet farmers. It is one of the common and major source of
protein and, at the same time improves the soil fertility by fixing Nitrogen. While it is
considered as a major crop, the quality is often affected by the pests and diseases.
Pests and diseases are the cause of yield losses in crops around the world. Modern
agriculture has been trying to cope up with this problem using pesticides and chemicals,
but at the expense of human health and environment. As more farmers practice the tree-
crop combination, there is a significant potential for a decrease in traditional pest and
disease problem. The diverse vegetation (tree-crop and non-crop) leads to the
minimization or complete avoidance of using chemical pesticides, and thereby
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
3
maintaining a balanced and sustainable ecosystem that is socially just, healthy and
environmentally sound.
This study can be used to help the great mass of resource poor farmers by
reducing their reliance on scarce and expensive agrochemical inputs, and receive
maximum returns under low levels of technology. Economically, it minimizes the cost of
pesticides, fertilizers, health risk, labor, and time.
The study aimed to: 1) to compare the incidence of pest and disease occurrence
between the bush bean grown with trees and the bush bean grown in conventional
method, and, 2) to identify and compare the number and kinds of pest occurrence
between bush bean grown with tree and bush bean grown in conventional method.
This research study was conducted at the Agroforestry Experimental Area,
College of Agriculture, Benguet State University from December 2008 to April 2009.
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
REVIEW OF THE LITERATURE
Plant communities that are modified to meet the special needs of humans become
subject to heavy pest damage, and generally the more intensely such communities are
modified, the more abundant and serious the pests. The effects of the reduction of plant
diversity on outbreaks of herbivore pests and microbial pathogens are well documented in
the agriculture literature (Andow, 1991 as cited by Collins and Qualset, 1999).
Several studies have shown that it is possible to stabilize the insect communities
of agroecosystems by designing and constructing vegetational architectures that support
populations of natural enemies or that have direct deterrent effects on pest herbivores
(Perrin, 1980; Risch et al., 1983 as cited by Collins and Qualset, 1999).
There are various factors in crop mixtures that help constrain pest attack. A host
plant may be protected from insect pests by the physical presence of other plants that may
provide a camouflage or a physical barrier. The odor of some plants can also disrupt the
searching behavior of pests (Altieri, 1994 as cited by Collins and Qualset, 1999).
Yet, along with the trees might come small wasps that seek out the nectar in the tree
flowers. These wasps may in turn be the natural parasitoids of pests that normally attack
the crops. The wasps are part of the associated biodiversity. The trees, then, create (direct
function) and attract wasps (indirect functions) (Vandermeer and Perfecto, 1995 as cited
by Collins and Qualset, 1999).
Certain weeds (mostly Umbelliferae, Legumiosae and Compositae) play an
important ecological role by harboring and supporting a complex of beneficial arthropods
that aid in suppressing pest populations (Altieri and Whitcomb, 1980 as cited by Altieri,
1994).
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
5
Overwhelming evidence suggests that polycultures support a lower herbivore load
than monocultures. One factor explaining this trend is that relatively more stable natural
enemy populations can persist in polycultures due to the more continuous availability of
food sources and microhabitats (Letourneau and Altieri, 1983; Helenius, 1989; as cited
by Altieri, 1994). The other possibility is that specialized herbivores are more likely to
find and remain on pure crop stands, that provide concentrated resources and monotonous
physical conditions (Tahvanainen and Root, 1972 as cited by Altieri, 1994).
However, based on current ecological and agronomic theory, low pest potentials
may be expected in farms with a dominant perennial crop component. It is considered to
be semi permanent ecosystems, and more stable than annual crop systems. Since it suffer
fewer disturbances and are characterized by greater structural diversity, possibilities for
the establishment of biological control agents are generally higher, especially if floral
undergrowth diversity is encouraged (Huffaker and Messenger, 1976: Altieri and
Schmidt, 1985 as cited by Altieri, 1994).
Crops lush from too much Nitrogen are more attractive to pest and fungal
diseases. The reproductive rates of most pest insects are proportional to the supply of
certain amino acids in their diet. Excess fertility increases the supply of these amino acids
and plant tissue and the pest numbers too rapidly, which is true in a conventional farming
system. Plants fertilized by the slow release of nutrients from natural decomposition are
more resistant to insect and disease than crops fertilized by the highly soluble nutrients
provided by the inorganic fertilizers (COG’S Organic field crop handbook, 2008).
Many of the conventional farming practices that enhance yields also contribute to
increased pest problems. The wide spread use of a broad-spectrum pesticides kills not
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
6
only the crop pests but also the insect, mites, and nematodes that functions as natural
enemies of pests. Farmers have found that repeated application of pesticides over twenty
or more generation of the pest all too frequently results in the development of pest
populations that are resistant to the pesticides. These are pests that were held in check by
natural enemies and caused no economic damage in a natural habitat (Chrispeels and
Sandra, 1994).
Many studies have documented the movement of beneficial arthropods from
margins into crops, and higher biological control is usually observed in crop rows close
to wild vegetation edges than in rows in the center of the fields (Altieri, 1994).
In general, agroecosystems that are more diverse, more permanent, isolated, and
managed with low input technology (i.e., agroforestry systems, traditional polycultures)
take fuller advantage of work done by ecological processes associated with higher
biodiversity than do highly simplified, input-driven, and disturbed systems (i.e., modern
row crops and vegetable monocultures and fruit orchards) (Altieri, 1995 as cited by
Collins and Qualset, 1999).
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
MATERIALS AND METHODS
The study was conducted at the Agroforestry Experimental Area, College of
Agriculture, Benguet State University from December 2008 to April 2009. The materials
used were bush bean seeds of Kabayan variety (1.5 kg), fertilizer (16-16-16 and
compost), pH meter, and farm tools and implements.
Two plots with approximately the same area (i.e. 120 sq. m) were planted with
bush bean in two different locations. The first plot was planted with the bush bean in a
conventional farming system (monoculture) as Treatment 1 (Fig. 1) and fertilized with
inorganic fertilizer (16-16-16). The plant-to-plant distance was 25 cm. In contrast, the
second plot was planted with bush bean in combination with existing trees and woody
species and other species of plants (wild or domesticated) as Treatment 2 (Fig. 2). The
plant-to-plant distance was 25 cm, and was treated with organic fertilizer (compost and
compost leachate). Both Treatments were not treated with pesticide. Both treatments
were replicated three times. The treatments were as follows:
T1 = Conventional method: Inorganic fertilizer (16-16-16), weeding, tilling, and no
pesticides.
T2 = Tree-crop combination: Organic fertilizer (compost and compost leachate), no
weeding, minimum tillage, and no pesticides.
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
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Figure 1. Bush bean planted in a Conventional method (Treatment 1)
Figure 2. Bush bean planted in a Tree-crop combination (Treatment 2)
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
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Data Gathered
The following data were gathered from the experiment:
A. Incidence of Insect Pest and Diseases (%). A weekly evaluation of the crop was done.
The following formula was used in computing the percentage degree of pest and
disease incidence (DOI):
Total No. of Plants - No. of Infected/Injured Plants
DOI = x 100
Total No. of plants
B. Soil Properties
1. Soil pH. The initial and final pH of the soil was determined before planting and
after harvest using the pH meter respectively.
2. Organic matter content (%). Organic matter content was analyzed by using the
Walkley Black method.
3. Nitrogen content (%). The nitrogen content of the soil was derived from OM
content of the media following the formula:
%N = %OM (0.05)
Where: 0.05 = constant
4. Phosphorus content (%). The phosphorus content was analyzed using the
spectrophotometer.
C. Yield and Yield Component
1. Number of days from planting to harvesting. The number of days from the
planting to harvesting of bush bean was recorded.
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
10
2. Marketable yield per treatment (kg). Marketable yield per treatment was
taken after harvest. Marketable yield was slightly or disease free, no mechanical injury,
standard grade and of good quality.
3. Non-marketable yield per treatment (kg). Non-marketable yield per treatment
was taken after harvest. Non-marketable yield was disease and pest infected,
mechanically injured, poor grade and of poor quality.
4. Total yield per treatment (kg). The total yield per treatment was taken after
harvest. The total yield was the sum of marketable and non-marketable product.
D. Inventory of Plant and Insect Species
Different species of trees, weeds, and insects were identified.
E. Growth Increment (cm)
The height of the bush beans grown in both treatments were taken on weekly
basis from one month after the sowing of seeds till the first harvest to determine
the growth increment.
F. Return on Investment (%). This was computed after the bush bean was harvested by
using the formula:
Gross Sales – Total Expenses
ROI =
x 100
Total Expenses
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
RESULTS AND DISCUSSION
Disease Incidence
Bean Rust (
Uromyces phaseoli)
Table 1 presents the data on incidence of bean rust disease (Fig. 3) in bush bean
grown in the two specified treatments in terms of percentage incidence.
The data shows that in case of Treatment 1 or conventional method the mean
degree of incidence was 77.67%, which according to the rating index is very severe. On
the other hand, the mean degree of incidence was 14.33% in the tree-crop combination.
We can therefore, observe the significantly large difference in the degree of
incidence of bean rust between the two treatments.
The implication of these findings is that planting bush beans with trees and
diverse plants mitigates if not significantly prevents the occurrence of bean rust in bush
bean.
Table 1. Mean degree of bean rust incidence (%)
TREATMENT
MEAN
Conventional method
77.67
Tree- crop combination
14.33
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
12
Fusarium wilt (
Fusarium oxysporum)
The data on Table 2 presents the incidence of Fusarium wilt disease on bush bean
(Fig. 4.a and 4.b) planted in two different conditions.
In the case of Treatment 1, the mean incidence percentage was 62%, which
evidently is very high. In the case of bush bean planted with trees and non-crop plants,
there was completely no incidence of root rot.
The finding is very significant and given the condition of the experiment, trees
along with other domesticated or wild plants near the bush bean prevents the occurrence
of Fusarium wilt which is caused by the
Fusarium oxysporum. One of the reason could be
crops lush with too much Nitrogen which was true in the case of Treatment 1 (16-16-16)
attracts a fungal diseases (Anonymous).
Table 2. Mean degree of Fusarium wilt incidence (%)
TREATMENT
MEAN
Conventional method
62
Tree- crop combination
0
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
13
Leaf Curling (Bean Common Mosaic Virus)
Table 3 shows the data on the incidence of leaf curling disease in bush bean (Fig.
5) grown in conventional method and bush bean grown in tree-crop combination.
The data shows that a mean degree of incidence of leaf curling disease in
conventional method was 56.67% while the mean degree of incidence of leaf curling in
tree-crop combination was 9.67%, which shows a large difference in leaf curling
occurrence between the two treatments. The incidence of leaf curling disease was
significantly higher in conventional method than the tree-crop combination. The result
shows the probability of leaf curling occurrence is more on the bush bean grown in
conventional method.
Table 3. Mean degree of incidence of leaf curling (%)
TREATMENT
MEAN
Conventional method
56.67
Tree-crop combination
9.67
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
14
Figure 3. Bean rust (
Uromyces phaseoli) infected leaves
Figure 4.a. Fusarium wilt (
Fusarium oxysporum) infected plant
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
15
Figure 4.b. Root infected by Fusarium wilt
Figure 5. Leaf curling caused by Bean Common Mosaic Virus
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
16
Pest Incidence
Pod Borer (
Maruca vitrata (Testulasis) Geyer)
The data shows the pod borer occurrence in the conventional method was
significantly higher compared to the tree-crop combination (Table 4).
The mean of the pod borer incidence (Figure 6) in conventional method was 45%
while the mean pod borer incidence in tree-crop combination was 7.33%. The result
indicates that the pod borer is more prone to the bush bean grown in conventional method
rather than grown with trees and other non-crop plants. Altieri (1972) reported that
specialized herbivores are more likely to find and remain in pure crop stands that provide
concentrated resources and monotonous physical condition than in a mixed crop stands.
Table 4. Mean degree of incidence of pod borer (%)
TREATMENT
MEAN
Conventional method
45.0
Tree-crop combination
7.33
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
17
Leaf Miner (
Liriomyza huidobrensis Blanchard)
Significant difference was observed in the incidence of leaf miner among the bush
bean in conventional method and bush bean in tree crop combination (Table 5).
The data shows the mean of leaf miner incidence (Figure 7) in conventional
method was 65.33% and the mean of leaf miner incidence in tree-crop combination was
25%. This result corroborated the study of Letourneau and Altieri (1983) that the
population of natural enemy of pest is relatively more stable in polyculture as it provides
continuous food sources and favorable microhabitats. Many other ecological theories also
approve the findings of this experiment which exhibited the large difference in pests and
diseases occurrence between the bush bean planted in a conventional method
(monoculture) and the bush bean planted with trees and non-crop plant species
(Agroforestry).
Table 5. Mean degree of incidence of leaf miner (%)
TREATMENT
MEAN
Conventional method
65.33
Tree-crop combination
25.00
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
18
Figure 6. Pods infected by pod borer (
Maruca vitrata (Testulasis) Geyer)
Figure 7. Leaf injured by the larva of leaf miner (
Liriomyza huidobrensis Blanchard)
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
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Soil Properties
The result (Table 6) of the soil analysis done before planting and after harvesting
shows that in the case of the conventional method, there was a slight increase in pH
value, organic matter (OM) content and nitrogen (N) content but there was decrease in
phosphorous (P) content. In the case of tree-crop combination, the result showed a slight
increase in organic matter content and nitrogen content but there was a slight decrease in
pH and decrease in the phosphorous content. The decrease in pH in case of tree-crop
combination was due to the elevation of the Carbon dioxide (end product of OM)
concentration in the soil air can lower the soil pH, by formation and dissociation of
carbonic acid (Singer and Munns, 2002). The decreases in Phosphorous content in both
treatments were attributed to the higher requirement of Phosphorous by bush bean
(50(N)-120(P)-50(K) per ha).
Table 6. Initial and final pH, OM, N and P (%)
INITIAL
FINAL
TREATMENT
pH OM N P
pH OM N P
Conventional
method
5.685 2.15 0.1075 31.59 6.080 2.18 0.1090 21.12
Tree-crop
combination
5.590 2.74 0.1370 63.18 5.365 2.77 0.1385 29.17
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
20
Yield and Yield Components
Marketable Yield Per Treatment (kg)
Table 7 presents the marketable yield as affected by the two treatments.
Significant differences were observed among the treatments. The mean marketable yield
of bush bean produced by the conventional method was 7.7 kg and the mean marketable
yield produced by the tree-crop combination was 10.3 kg. In addition, the marketable
yield produced by tree-crop combination can be considered of better quality than the
marketable yield produced by the conventional method. This is because bush bean
obtained from the tree-crop combination was organic, applied with organic fertilizer
(compost and compost leachate) and was without any chemicals.
Table 7. Marketable yield (kg)
TREATMENT
MEAN
Conventional method
7.70
Tree-crop combination
10.3
Non-Marketable Yield Per Treatment (%)
Contrasting non-marketable yield was statistically revealed (Table 8). Statistical
analysis showed a significant difference in non-marketable yield produced by
conventional method and tree-crop combination. The mean non-marketable yield
obtained from the conventional method was 4.27 kg while the mean non-marketable yield
obtained from tree- crop combination was only 0.42 kg. The high non-marketable yield in
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
21
case of conventional method was due to the high degree of incidence of Fusarium wilt,
root rot, leaf curling, pod borer, and leaf miner. It was also due to the unmarketable shape
(curly pod) and size of the bean pods.
Table 8. Non-marketable yield per treatment (kg)
TREATMENT
MEAN
Conventional method
4.27
Tree-crop combination
0.42
Total Yield Per Treatment (kg)
The total yield, which includes both, the marketable yield and non-marketable
yield is shown in Table 9. The mean total yield produced by conventional method was
11.97 kg and the mean total yield produced by tree-crop combination was 10.65 kg which
shows no significant difference in total yield . But, the data also showed (Table 7 and 8)
there was comparable marketable yield but very low non-marketable yield in case of tree-
crop combination, while in case of conventional method the non-marketable yield was
more than half of the marketable yield. Therefore, from an economical point of view it is
concluded that, conventional method will generate less income as compared to the tree-
crop combination.
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
22
Table 9. Total yield per treatment (kg)
TREATMENT
MEAN
Conventional method
11.97
Tree-crop combination
10.65
Length of Pod (cm)
Shown in Table 10 are the average length of bush been pod. The mean length of
pod gathered from conventional method was 15.67 cm and the mean length of pod
gathered from tree-crop combination was 16.74 cm. The longer length of pod in tree-crop
combination may be attributed to the longer plant height (fig. 8), which allowed the pod
to grow vertically downward without being disturbed by the soil surface. Lower sunlight
exposure as obstructed by higher plants in the surrounding (Treatment 2) caused the
plants to grow higher because the growth hormone (auxin) in the shaded side of the
plants were stimulated (Devlin and Witham, 1983).
Table 10. Mean length of pod (cm)
TREATMENT
MEAN
Conventional method
15.67
Tree-crop combination
16.74
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
23
Number of Days from Planting to Harvesting
Number of days from planting to the harvesting of bush bean was 62 days.
Height Increment (cm)
The data in Figure 8 presents the weekly height increment of bush bean grown in
conventional method and tree-crop combination. There was a significant difference in the
height increment. The mean initial height (one month from sowing of seed) of the plant
was 18.06 cm and the mean final height at the time of first harvest was 32.06 cm in
conventional method. On the other hand, the mean initial height was 27.47 cm and the
mean final height at the time of first harvest was 39.04 cm. However, the differences in
height of plants were the result of sunlight availability. The plants on the shaded sides
(Treatment 2) elongated in much greater rate than on the illuminated side. This
differential growth response of the plant to light, was caused by the unequal distribution
of auxin, the higher concentration of growth hormone (auxin) being on the shaded side
(Devlin and Witham, 1983).
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
24
Conventional method
45
Crop-tree combination
40
35
)
30
(
c
m
25
e
i
g
ht
20
h
15
l
a
nt
P
10
5
0
1st
2nd
3rd
4th
5th
Weeks
Figure 8. Weekly height increment (cm)
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
25
Return on Investment
Table 11 shows the return on investment (ROI) from conventional method and
tree-crop combination. The sales of the bush bean produced by the tree-crop combination
was considered organic and valued accordingly to the market price of organic beans.
Table 11. Return on investment (%)
TREATMENT
EXPENSES
SALES
ROI (%)
Conventional Method
639.5
693
8.37
Crop-Tree Combination
519.5
959
84.67
Bean = PhP 25/kg
Organic bean = PhP 31.5/kg
16-16-16 = PhP 40/kg
Compost = Php 100/bag
Been seed = PhP 250/kg
Trees (woody) and Non-woody Plant Species
The tree or woody (Fig. 9) and non-woody (Fig. 10) plant species in a tree-crop
combination farm were identified and captured in a photograph.
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
26
Calliandra-
Alumit (Hagimit)-
Calliandra calothyrsus Meissn.
Ficus minahassae
Bottle brush tree-
Tibig-
Callistemon citrinus
Ficus nota (Blanco) Merr.
Guava –
Fire tree-
Psidium guajava L.
Delonix regia
Figure 9. Woody species found in the Tree-crop combination
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
27
Japanese summer grape fruit-
Arabica Coffee-
Citrus paradisi
Coffee arabica
Trumpet flower-
Brugmansia suavolens
Pegion pea-
(Humb. et Bompl.) Brecht et Presl
Cajanus cajan
Rattan-
Calamus merrillii Becc.
Gmelina –
Gmelina arborea
Fig. 9. Woody species found in the Tree-crop combination (continued)
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
28
Gumamela (Turk’s cap)–
Tiesa
Malvaviscus arboreus
Pouteria campechiana (HBK.)
Santol -
Sandoricum koetjape
Tawa tawa-
Ricinus communis L.
Dapdap-
Erythrina variegata Linn.
var. orientalis (Linn.)
Figure 9. Woody species found in the Tree-crop combination
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
29
Alternanthera-
Carabao grass-
Axonopus compressus
Alternanthera sessilis
(Sw.) P. Beauv.
Beray -
Bidens pilosa L. var pilosa
Bandera de español-
Canna indica L.
Taro-
Colocasia esculenta
Japanese weed-
Crassocephalum crepidioides
Figure 10. Non-woody species found in the Tree-crop combination (continued)
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
30
African star grass-
Spanish drymaria-
Cynodon nlemfuensis
Drymaria cordata (L.)
Small flower Galinsoga-
Sweet potato-
Galinsoga parviflora
Ipomea batatas L.
Napier grass-
Kangingit-
Pennisetum purpureum Schumach.
Polygonum perfoliatum L.
Figure 10. Non-woody species found in the Tree-crop combination (continued)
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
31
Taingang daga
Wild sunflower -
Oxalis corniculata L.
Tithonia diversifolia
Wild rose-
Rosa philippinensis
Amti -
Solanum nigrum L.
Sayote -
Sechium edule L.
Banana-
Musa sp.
Figure 10. Non-woody species found in the Tree-crop combination (continued)
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
32
Inventory of Insects
Both the beneficial insects and the insect pests from both conventional method
area and the tree- crop- combination area were identified and shown in Table 12. It was
found out that there was a balance in between the beneficial insects and the insect pests in
the tree-crop combination, while in the conventional method there was only the presence
of insect pest.
Table 12. List of insects found in the study areas
A. Insects identified from the conventional method
1. *Leaf miner
Liriomyza huidobrensis (Blanchard)
2. *Pod borer
Maruca vitrata (Testulasis) (Geyer)
3. *Aphid
Aphis craccivora
4. *Cabbage Butterfly
Pieres rapae (L.)
5. *Leaf roller
Sylepta derogate (Fabricus)
6. *Vinegar fly
Drosophila melanogaster
7. *Tussock moth
Dasychira spp.
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
33
B. Insects identified from the tree-crop combination
1. *Two spotted spider
Tetranychus sp.
Mites
2. *Army worm
Spodoptera litura (Fabricius)
3. *Mealy bug
Phenacoccus solani (Ferris)
4. *Leaf miner
Liriomyza huidobrensis (Blanchard)
5. *Tussock moth
Dasychira spp.
6. *Pod borer
Maruca vitrata (Testulasis) (Geyer)
7. *Semi looper
Anomis flava (Fabricius)
8. Ear wigs
Euborellia annulata
9. Honey bee
Apis mellifera
10. *Legume weevil
Callosobrochus maculates (Fabricius)
11. Two spotted
Aphanocephalus bimaculatus
coccinelid beetle
12. Soldier beetle
Chauliognathus lugubris
13. *Aphid
Aphis craccivora
14. Jumping spider
Sandalodes spp.
15. Wolf spider
Hogna helluo
16. Mirid bug
Stenodema laevigatum
17. Big eyed bug
Geocoris punctipes
18. Tent spider
Cryptophora cephalotes (Simon)
19. *Mole cricket
Gryllotalpa Africana (Pal de Beauvres)
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
34
20. *Cabbage Butterfly
Pieres rapae (L.)
21. Pygmy grass
Aeromachus pygmaeus
hopper
22. Spider ants
Mallinella shimogianai
23. *Plant hopper
Siphanta acuta
24. Pirate bug
Orius insidiosus
25. *Vinegar fly
Drosophila melanogaster
26. Long legged fly
Condylostylus spp.
27. Brachonid wasp
Allurus muricatus
28. *Leaf roller
Sylepta derogata (Fabricius)
* = Insect Pest
= Beneficial insect
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
SUMMARY, CONCLUSION AND RECOMMENDATION
Summary
The study was conducted at the Agroforestry Experimental Area, College of
Agriculture, Benguet State University, La Trinidad, Benguet from December, 2008 to
April, 2009 to compare the pest and disease incidence on the bush bean grown in
conventional method (monoculture) and the bush bean grown in tree-crop, and non-crop
combination (Agroforestry).
`
Statistical analysis showed a significant difference in the disease and pest
incidence among the treatments. The bush bean planted in conventional method showed
considerably higher percentage of disease ( bean rust, Fusarium wilt, and leaf curling)
and pest (pod borer and leaf miner) incidence as compared to the bush bean planted with
trees combined with the other non-crop plants.
In addition, results also revealed that non-marketable yield from the conventional
method was significantly higher than the non-marketable yield from the plants grown
with the trees and non-crop plants. However, the marketable and the total yield from both
the treatments were not significantly different. Nevertheless, ROI from tree-crop
combination was significantly higher compared to the ROI from the conventional
method.
Conclusion
Based on the result, it is concluded that planting with trees and different plant
species noticeably prevents the disease and pest incidence in the bush bean as compared
to the conventional method.
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
36
Recommendation
Planting of bush bean in combination with trees and other different plant species
is recommended to control the disease and pest occurrence in bush bean. However,
studies to understand the contribution of different plant and animal species, and other
physical components in controlling the pest and disease in a tree-crop combination are
encouraged.
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
LITERATURE CITED
ALTIERI, M. A. 1994. Biodiversity and pest management in agroecosystem.
Binghamton, New York. Food products press. Pp. 11-66, 65-92.
ANONYMOUS. COG’S Organic Field Handbook. Chapter 13. Retrieved on March 20,
2008 from www.Cog.ca.
CHRISPEELS, M. J and D. E. SANDRA. 1994. Plants, genes and crop biotechnology.
Canada. Jones and Bartlett. Pp. 439-442.
COLLINS, W. W. and C. O. QUALSET. 1999. Biodiversity in agroecosystem. Florida.
CRC press LLC. Pp. 69-141.
COLTING, L. M., B. C. LIGAT, L. G. LIRIO, J. C. PEREZ, J. P PABLO. 2003.
Compendium of insect pest and weeds associated with high value crops in the
Cordillera. Department of College of Agriculture. CHARM project and BSU.
Benguet. Pp. 4-50.
DEVLIN, R. M. and WITHAM, F. H. 1983. Plant Physiology 4th edition. Belmont,
California. Wadsworth Publishing Company. P. 376.
SINGER, M. J. and MUNNS, D. N. 2002. Soils an introduction 5th Edition. Upper
Saddle River, New Jersey. Pearson education, Inc. Pp. 158-159.
Effect of Tree-Crop Combination on the Pest and Disease Occurrence in
Bush Bean (Phaseolus vulgaris Linn.) / Raju Shrestha. 2009
Document Outline
- Effect of Tree-Crop Combination on the Pest and Disease Occurrence in Bush Bean (Phaseolus vulgaris Linn.)
- BIBLIOGRAPHY
- ABSTRACT
- TABLE OF CONTENTS
- INTRODUCTION
- REVIEW OF THE LITERATURE
- MATERIALS AND METHODS
- RESULTS AND DISCUSSION
- Disease Incidence
- Pest Incidence
- Soil Properties
- Yield and Yield Components
- Return on Investment
- Trees (woody) and Non-woody Plant Species
- Inventory of Insects
- SUMMARY, CONCLUSION AND RECOMMENDATION
- Summary
- Conclusion
- Recommendation
- LITERATURE CITED