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Project Title: Integrated Pest Management in Vegetables, Hot Pepper, Capsicum chinense (C3J03) 4.5.1 Programme: Commodity Improvement Programme 4.5.2 Goal: To reduce the cost of production and improve the quality of callaloo in selected areas of Jamaica 4.5.3 Justification Hot pepper (Capsicum spp.) is the third largest non-traditional crop with production increasing from 1,700 tonnes in 1998 to 9,000 in 1996. A range of pest such as aphid transmitted viruses and mite plagues the crop. Very little quantitative information is available on the extent to which these affect production. There is also very little documentation of other constraints that affect production. This sub-project seeks to determine the status of pest and other factors affecting hot pepper production as well as farmer knowledge of pests and sustainable control strategies. The information generated will be used to train farmers in the principles of Hot Pepper Integrated Pest Management. 4.5.4 Highlights
4.5.5 Activities 4.5.5.1 Activity1 - Epidemiology of the gall midge complex 4.5.5.1.1 Objectives
4.5.5.1.2 Methodology Study sites Four un-infested farms in St Mary, Clarendon and St Thomas with West Indian Red cv plant stands of 2,000 plants/farm) were selected. On each farm, the field will be divided into four quadrats of approximately 500 plants. Detection and observation of gall midge infestation Over a three-month period, farms were visited once per fortnight to collect samples. Fifty of the predominant (exhibited by >50% of crop stand) fruit stage (flowers, button, immature green or green mature) were collected from each quadrat and placed tagged bags. Samples from each quadrant will be dissected in the laboratory to determine position of initial infestation and infestation levels. Monitoring adult midge flight Five sticky traps were placed in each quadrat and at fortnightly intervals the number of trapped gall midge adults recorded. The relationship between adult flight and larval infestation will be analyzed. 4.5.5.1.3 Results and Discussion Gall midge larvae have been found in samples collected on three of the four study farms. Highest populations were found in St Mary ranging from 0.5-27.0% infestation. On other farms infestation was lower and the gall midge population had decreased from initial levels when subsequent samples were taken. On the infested farm in Clarendon larval populations had fallen below detectable levels although sticky traps detected the presence of gall midge adults. Pesticide application schedules and types of pesticides used on each farm will be examined to see the relationship between pesticide use regime and gall midge populations. 4.5.5.2 Activity 2 Effect of cultural practices and chemical insecticides on infestations of the gall midge complex (Prodiplosis longifila and Contarinia lycopersci (Diptera: Cecidomyiidae) affecting hot pepper exports to the USA. 4.5.5.2.1 Objective To determine the effectiveness of cultural practices in combination with synthetic pesticides to reduce larval infestations 4.5.5.2.2 Methodology Season I The study was conducted at the CARDI Field Station on pepper plants established in December 1997. The study site consisted of six plots each having a total of 48 plants. Treatments evaluated included cultural practices and the application of chemical insecticides (contact and systemic). Cultural practices involved thorough field sanitation - pruning and stripping trees, removal and destruction of crop residues. These practices were conducted at the beginning of the study and repeated whenever needed. Four insecticides were evaluated, Imidacloprid (Admire ®, foliar and soil application) Fipronyl (Regent ®), Malathion and Diazinon. Treatments were applied at the recommended rate during the late afternoon after cultural practices were conducted. Applications were made with a hand held Sissmex applicator. A threshold of 5% fruit infestation was used as a guide to for re-application of treatments. Larval populations were assessed pre and post treatment, the later being conducted weekly. Assessments were made by removing 10 pepper fruits from six plants (located at the top, middle and bottom sections of the plot) and dissecting the pedicels and calyx of fruits to determine larval infestation and mortality. Season II The study was initiated in March 1999 at the CARDI-DTC. Experimental Design Treatments mentioned above were allocated in a randomized complete block design with 4 replicates. Each plot consists of 30 plants inclusive of guard plants. The methodology was similar to season I, however additional parameters were measured - residue levels on marketable fruits and cost benefit analyses. Pesticide residue levels on marketable fruits will be determined 1, 3, and 5 weeks after treatments. Researchers from the University of the West will conduct residue analyses. Cost benefit analyses (economic, environmental) will be conducted for each treatment combination being evaluated. Economic analyses will be based on a comparison of the cost of inputs (supplies, casual labour, treatment application, and irrigation) versus returns on marketable yields. Environmental analyses will be conducted by determining by pesticide residue levels on marketable fruits, persistence in the soil and the incidence of natural enemies. 4.5.5.2.3 Results and Discussion Season I Gall midge populations were significantly reduced after cultural practices and insecticides were applied; mean reduction in midge population across treatments was 47.6% (Figure 3). This initial treatment held midge populations below the 5% threshold in plots treated with immidachloprid and fipronyl. For Malathion and Diazinon however, 3 applications had to be made before populations were reduced below the threshold. For the duration of the study, a total of 1 application was made for immidachloprid, 2 for fipronyl and 3 applications made for Diazinon and Malathion. Across plots, during the last 2 weeks of observation, populations increased significantly above the 5% threshold (mean population levels). These observations could be due in part to the rainfall patterns being experienced during the period of the study, natural population emergence as well as the crop phenology. These factors are being examined. The study will be repeated on farms within the target areas. Season II Gall Midge Incidence. To date, pest has been observed in flowers and green mature fruits at levels of 0.01% and 0.04% respectively. As a result of the low pest incidence, treatments have not yet been applied. Figure 1. Effect of Cultural Practices on Gall Midge Infestations. [Arrows indicate treatment dates - Chemical treatments (red arrows) - 16th November, 26th November, 4th December, 18th December. Cultural practices (green arrows) - 14th November, 16th December, Dotted line (----) indicates 5% threshold] 4.6 Project Title: Enhanced Hot Pepper Production Technology (T1J11) 4.6.1 Programme: Technology Adaptation and Application 4.6.2 Goal To improve foreign exchange earnings through enhanced hot pepper production in selected parishes by the adoption of enhanced and sustainable technologies. 4.6.3 Justification In the Eastern Caribbean the English-speaking Islands including Grenada, St Vincent, St Lucia and Dominica have exploited over the past five years the market opportunities in the USA, Canada and Europe for the West Indian Red cultivar. In fact the pepper crop has been able to ease the impact of the drastic decline of the banana industry on small farmers in particular in St Lucia, Dominica and St Vincent. Female farmers can benefit themselves from the available market for the West Indian Red pepper. The readily available market, the available seeds produced by CARDI in Antigua and Barbados Seed Units, available air transport to the market, and a favourable price of the product EC$1.00 per lb. all contributed to five years of sustained and expanded growth of hot pepper production. CARDI has also in addition to producing the seeds for the crops, the Institute has also developed a technology package for growing the crop and produced information bulletins and fact sheets on diseases of peppers in the Caribbean. The Institute is also continuing research and updating its pest management strategies and also its production technologies. On a longer term basis CARDI is presently planning strategies to improve the seed germplasm through a series of breeding work. Jamaica is known to be an important producer of the Scotch Bonnet cultivar, a yellow with a typical fruit shape mainly for local consumption. However this cultivar (variety) is known to succumb much faster than the West Indian Red to the pest and diseases. Whitefly (Bemisia tabaci), aphid vectors, gemini viruses (in the OECS), Tobacco Etch and Potato Virus Y (in Jamaica) and bacterial spot are the common pests and diseases of Scotch Bonnet and which seriously limit its potential. The West Indian Red seems to be a much harder cultivar and stands up well to the attacks of vector/ viruses and able to produce an economic crop over a reasonably good season of six months. The hot pepper crop is also recognized as a suitable crop for small farmers (0.005 ha) or 1000 plants. A weekly income of over J$10,000.00 at the moment is guaranteed, if the proper marketing is developed to the USA, and elsewhere if the level of production so allows. The Institution has also identified the pepper crop as one of the major commodities to be developed through an interdisciplinary approach to crop management. The technology may still need refinement but a series of adaptive research is continuing to further the development of this crop throughout its member countries. All governments have depended on CARDI to assist in pushing their pepper crop, apart from the provision of the seed material of high quality as previously mentioned. CARDI/Dominica reported spacing trials in order to arrive at an optimum plant density. Out of this work spacing of between banks or ridges 1m or within the rows 60cm was recommended (CARDI Annual Report 1993/1994 Dominica). This work is on going. A technical production bulletin is in the press. The Project Manager (coordinator) has been associated with the crop during the past five years in pathology and agronomy research and has collaborated with the Plant Breeder to assess pepper germplasm in Barbados. A Fact Sheet, Important diseases of hot pepper in the Caribbean Community Countries was written by this scientist The rest of the project management team includes soil scientist and entomologist of the CARDI Jamaica Unit both of whom have experiences respectively in the nutrient and pest problems of pepper in Jamaica 4.6.4 Activities 4.6.4.1 Activity 1: Validation of advanced technologies in hot pepper production - varietal, crop management (mulch, imidacloprid foliar and soil) 4.6.4.1.1 Objectives To validate improved technologies for increasing yield and income 4.6.4.1.2 Methodology A randomized replicated experiment was conducted to evaluate the potential of different permutations and combinations of cultural and chemical controls to increase yields and income. The experiment consisted of six treatments (5 replicates): -
The trial was laid out as illustrated in Figures1 and 2. Plants were irrigated every two days using a drip system. Fertilizer applications were made as follows-
Monitoring incidence of virus Dot blots were taken from ten randomly selected experimental plants at three intervals 1) at start of bearing, 2) peak bearing and 3) at end of experiment (after eleven weeks of harvest). The blots will be analyzed for virus incidence in each plot. The height and width of the ten blotted plants were also recorded. Pest damage and crop loss assessment At 50 % bearing all green mature and ripe peppers were removed from experimental plants in each plot and the fresh weight of yield per plant were calculated based on plant stand and number of plants bearing (this corrected for delay in productivity of resupplied plants). From each experimental plot 25 of the harvested peppers were removed and the following data taken for each sub-sample:
Data from plots were analyzed using Analysis of variance (JMP statistical software) to compare treatment differences and determine the combination(s), which gave the highest marketable yield. Data on the cost of option specific inputs were recorded for each treatment. A cost-benefit analysis will be performed for each production technology to determine the best option. 4.6.4.1.3 Results and Discussion Yields From fresh weight data collected, all mulched plots gave higher yields and larger (longer) peppers than un-mulched plots (Table 5). The diameter of the fruits was not significantly (P>0.05) different among treatments. Throughout the duration of this experiment (November1999 to March 2000) the plants were subjected to severe drought conditions. The effect of the mulch in reducing evapotranspiration proved advantageous in mulched plots and its benefits were reflected in increased yields by 78% to 138%. Mulching also resulted in the added benefit of suppressing weed growth and hence weed management costs. Table 1: Mean yield per plant and size of fruits obtained using different production technologies
NB- Bracketed figures represent Standard Error of Means (SEM) Gall midge incidence There was a variation in the incidence of gall midge among treatment plots (Table 6). Although these differences were not significant (P>0.05) treatment plots receiving foliar applications of insecticide (Control, M0x If and M1x If) had lower gall midge incidence than plots treated with soil drench, imidacloprid (M0x Is and M1x Is) or received no insecticidal traeatment (M1). The control plots were sprayed every two weeks with lambda cyhalothrin and these plots had the lowest gall midge incidence but this difference after five pesticide applications was of little economic benefit compared to a single foliar application of imidacloprid. Reflective mulches are purported to reduce the landing efficiency of aphids thus reducing aphid populations on plants. This hypothesis was extrapolated to gall midges in this experiment however; the reflective mulch appeared to have no deterring effect on invasion by gall midge adults. Table 2: Gall midge incidence
in fruits from plots maintained using different production technologies
NB- Bracketed figures represent Standard Error of Means (SEM) Table 3: Crop loss assessment
4.6.4.2 Activity 2 - Technology Transfer and Farm Management in Hot Pepper 4.6.4.2.1 Objectives
4.6.4.2.2 Methodology Establishment of demonstration plots. Demonstration plots were established in four (4) parishes - St Mary, Clarendon, St Catherine and St Thomas. On these plots the best technologies generated under several projects inclusive of the IPM CRSP was used to enhance current production technologies. Farms were monitored monthly to determine production and pest management practices, cost of inputs and income generated. Production Technology
Technology Transfer Technology transfer sessions were held to train farmers in the hot pepper IPM technology. Topics covered in the sessions included: pest identification, fertility management, and principles of IPM. Technology transfer sessions were not only geared at production technology but also demonstrated the benefits of developing a sound marketing strategy i.e. an integrated approach to hot pepper production and marketing. Demonstration plots were used in the technology transfer process. 4.6.4.2.3 Results and Discussion Improved production technologies of hot pepper (West Indian Red cv.), introduced to small farmers in selected parishes have contributed to the development of a viable and sustainable hot pepper industry in Jamaica. Ten demonstration sites were established since the inception of the project in five parishes namely Clarendon, St Catherine, St Mary, Manchester and St Thomas. On average, two thousand seedlings were transplanted on each pilot farm. Farmer adoption of technologies resulted in satellite farms having consistently good yields and the plant exhibiting the expected vigour and tolerance. In addition observations showed that fields continued to yield fruits of ideal size and quantity even after nine months of harvest. Participating farmers have verbally endorsed the superior productivity of the West Indian Red cultivar both in volume and duration of viability. Economic returns have been favourable and in one instance were equated to returns from an area of sugarcane twenty-fold larger than the 1.2-hectare demonstration plot. Local processors are now benefiting from the productivity of this cultivar and farmers have reported increased demand for this pepper from this market. With the growing availability of West Indian Red cv. some processors have noted that they have saved on importation of substitute hot pepper, as local supplies are now more reliable. Heavy rains in the months of July and August adversely affected four of the seven satellite plots that were established earlier this year (1999). Fields were overgrown with weeds, as farmers were unable to carry out any form of maintenance on the plots because of the heavy rains. This unfavourable weather condition has resulted in the premature termination of these holding reducing the number of active sites under the project. Table 4: Cumulative yields and gross returns on the nine pilot farms
In addition the harvesting of peppers was adversely affected by the wet weather condition, which resulted in the unavailability of marketable fruits towards the end of the third quarter. Gall midge complex (Contarina lycopersici and Prodiplosis longifila) infestation continued to have its impact on the hot pepper export trade as the mandatory regulation of fumigation of all hot pepper exports at port of entry in the United States is still being enforced. However infestation levels on the satellite farms remained below the economic threshold due to the farmers employing proper cultural practices and chemical control. 4.6.4.3 Activity 3 - Fertility Studies to Improve Yields of Hot Pepper 4.6.4.3.1 Objectives
4.6.4.3.2 Methodology Scotch Bonnet pepper seedlings were grown at the CARDI greenhouse facilities and then transplanted to the experimental plots at Bodles on 5 May 1998. The seedlings were planted 60 cm within rows and 90 cm between rows with a total of 18 plants per plot. Plots were watered by overhead sprinkler irrigation once to twice weekly. The experiment was a 3x3 factorial. The factors were nitrogen and phosphorus/potassium combinations. A randomized incomplete block design was used with four blocks. All phosphorus and 1/3 N and K were applied two weeks after transplanting on 6 May 1998. One-third nitrogen and potassium were applied on 26 June 1998 and 21 September 1998. Nitrogen was applied at 187, 374 and 747 kg/ha. Phosphorus was applied at 31 and 62 kg/ha while potassium was applied at 75, 150 and 300 kg/ha (Table 10). Table 5: Means of weight and total number of fruits per plot from eight harvests (natural log transformed data, with back transformations)
T1 (control, no fertilizer); T2 (187 kg
N/ha, 31 kg P/ha, 75 kg K/ha); T3 (374 kg N/ha, 62 kg P/ha, 150 kg K/ha);
T4 (747 kg N/ha, 62 kg P/ha, 300 kg K/ha); T5 (foliar application of NPK). Table 6: Nutrient levels (kg/ha) used in the various treatments
The plots were visited monthly and four inner plants assessed for symptoms of virus disease. Virus symptoms were scored using the following scale: 0 = no symptoms, 1 = vein clearing, 2 = mosaic, 3 = mosaic and leaf deformation and 4 = severe leaf deformation, mosaic and reduction in leaf size. The plants were also assessed for the presence of insect pests. They were divided into four sections based on the natural branching pattern of the plant and incidence scored (0-4) based on presence or absence on these sections. Plant height and spread (length by width) were also recorded monthly. Fifteen recently expanded leaves were also collected from each plot and assessed for N, P, K, Ca and Mg during peak production. Data were analyzed using AUNBALANCED and AREPMEASURES procedures in GENSTAT statistical software. Repeated measures analysis of variance was used to assess treatment effects (height, spread and pest incidence) over time. Data collection was completed in December 1998. 4.6.4.3.3 Results and Discussion Foliar nutrient levels The foliar nutrient levels for the various treatments are presented in Table 11. Significant differences were observed only for nitrogen (P=0.007). Foliar nitrogen levels increased with the level of nitrogen applied (Table 12). Foliar nitrogen levels in plots to which 187 kg/ha nitrogen was applied were below the sufficiency levels suggested by Lorenz and Maynard (1986) (Table 13). Plants in these plots may therefore be nitrogen deficient and may not grow and yield at optimum levels. Foliar phosphorus and magnesium levels for all treatments were well within the sufficiency range. However, potassium and calcium levels were below the sufficiency level for some treatments. Table 7: Suggested sufficiency levels of selected macronutrients in pepper leaves
Source: Lorenz and Maynard (1986) Table 8: Levels of nitrogen, phosphorus, potassium, calcium and magnesium detected in leaf samples collected from Scotch Bonnet pepper six weeks after transplanting
Table 9: Foliar nitrogen levels as a function of nitrogen levels applied
Growth The rate of increase in height and cover was significantly different among nitrogen treatments and was highest for plots to which the highest level of nitrogen was applied (P<0.05) (Figs 12 and 13). There was no significant growth response to P and K. Levels of P over 60 kg/ha and K over 75kg/ha did not give any appreciable growth increase. Assessment of the soil nutrient status indicated that the levels of P and K in the Bodles loam were considered moderate. This is probably due to application of fertilizers to the field station over the years. Yield There were no significant differences in yield (number of fruit or weight of fruit) among the treatments (Table 14). This suggests that combinations of lower levels of N, P and K are adequate to achieve good yields. The results confirm the findings of the previous study. Further work will now focus on the lower levels and will determine the best combination of N, P and K at these levels. Table 10: Variations in number of fruits and total fresh weight in response to fertilizer application.
Pest Incidence Table 11: Mean number of sections with insect pests
Infestation levels of aphids and mites varied significantly with time (P<0.01 and P<0.05) (Figs 14 and 15). However, there were no significant differences among the treatments. This is unlike the previous study where higher levels of aphids and mites were observed in plots to which higher levels of fertilizer had been applied. The mites impacted on yield in this study as defoliation was observed on plants with high mite levels. However, there were no significant differences in level of defoliation among treatments.
Figure 6: Variation of aphid population with time (May 1998 - Dec 1998)
Figure 7: Variation of number of sections with mites and number of sections defoliated with time (May 1998 - December 1998) Tobacco Etch and Potato Virus Y symptoms were observed in the plots from the first month of assessment (Fig 16). Myers et al (1998) reported 50% reduction in yield of Scotch Bonnet due to these viruses. As the virus score was similar among treatments, it is assumed that the virus impact was similar for all treatments.
Figure 8: Mean virus score over time: May 1998-Dec 1998 4.6.4.4 Follow-up pepper nutrient trial A companion study at the Bodles Station (Smith and McGlashan, Personal Communication) was designed to separate the individual N, P, K levels. On the basis of these results to date and those of Smith and McGlashan, it was decided to separate the various nutrients and to use lower levels. The trials so far have concentrated only on the Scotch Bonnet variety. The follow-up trial would include an assessment of the response of the West Indian Red variety to varying levels of N, P, and K. The latter variety has proven to be a heavier producer than Scotch Bonnet and is tolerant to several of the pest /disease complexes. 4.6.4.4.1 Methodology Table 12: Levels of selected
soil parameters in Maverly loam at Mona DTC
Table 13: Levels of N, P and K used in third pepper nutrient trial
The study compares two varieties of hot pepper, West Indian Red and Scotch Bonnet. The design used was a 3x2x2x2 factorial replicated twice for NxPxKxVariety. All of the P and K and 25% of the N were applied 2 weeks after planting. The remaining N will be applied in three equal doses at 2, 3 and 4 months after establishment. The sources of the nutrient were Ammonium Sulphate, Triple Super-Phosphate and Muriate of Potash for N, P and K respectively. The site was cleared of vegetation and ploughed. This was refined with a hand tractor. The plants were established without the use of ridges. Each plot consisted of four rows of eight plants spaced 60cm apart. The inter-row space was 90cm. A drip irrigation system has been established at the site and approximately 25mm of water are applied weekly. A water meter is being used to determine the total water use. A tensiometer has been installed in the field as a guide to ensuring that moisture deficiency is minimal. Rainfall events are monitored from an adjacent field using a rain gauge. Measurements of plant growth, incidence of selected pests, time to flowering and production will be made on six inner plants. Virus severity will be ranked from 0-2 in which 0 represents absence, 1 represents leaf mosaic and 2 indicate presence of virus disease. Leaf and soil samples from selected treatments will also be monitored for N, P, K, Ca and Mg. Soil pH and organic matter content will also be measured at intervals. 4.6.4.4.2 Status: Ongoing The study was established on December 07, 1999. At the end of the year all the P and K nutrients had been added as well as 25% of the N. 4.6.4.5 Activity 4: Effect of aluminium phosphide on larval gall midge mortality and hot pepper quality 4.6.4.5.1 Objectives
4.6.4.5.2 Methodology A total of 18.1 kg of West Indian Red peppers was harvested from the CARDI DTC (September 19th, 1998). Peppers were sorted with respect to export quality criteria (green mature, medium size, firm), and two pounds of fruits weighed and placed in each 16 cardboard boxes. Two boxes of pepper were then placed in each of 6 barrels (o22m3). With the exception of the control, 0.2g of Aluminium phosphide (Degescher Phostoxin pellets; Aluminium phosphide 55%, Inert 45%, batch # -3238) was placed within each barrel. All barrels were sealed with duct tape and stored at room temperature. After 6,12,24 and 48 hours, 2 barrels were opened - treated and untreated (control) and observations on phosphine emission (PH3), larval mortality and fruit quality recorded. Phosphine Gas Emission After each exposure period, the level of phosphine gas emitted from each barrel was measured with a Drager detector tube (CH31101) 0 (immediately) and 10 minutes after the barrels were opened. Reading was taken at the edge of the barrels as well as 1 and 3 meters away. Pest Mortality For each exposure period, the 2 boxes of pepper were removed from each barrel and peppers from both boxes mixed. A total of 25 peppers were removed, dissected and larval mortality determined. Any other pest observed within boxes or on fruits was also recorded. Fruit Quality An additional, 50 peppers were removed from boxes and stored at room temperature for one week. Fruit quality (fruit/stem rots, turgidity) was recorded daily. 4.6.4.5.3 Results and Discussion Emission Reading Phosphine gas was only detected on the edge of the barrel immediately after opening (0.1ppm). For all other positions and time, the gas was not detected. Due to the lack of supplies emission readings were only recorded, 48 hours after fumigation. Larval Mortality Significant differences were observed in the level of larval mortality of treated and untreated hot pepper. For all exposure periods, larval mortality in peppers treated with phosphine was >80%, whereas for untreated fruits, larval morality never exceeded 12% (Table 18). Table 14: The effect of phosphine on the mortality of the larval stage of the gall midge complex
Fruit Quality For all exposure times, the number of marketable fruits remaining after 3,4, 6,or 7 days after harvest did not differ between treatments (Table 19). The study is being repeated and data will be analyzed. Table 15: Fruit quality after exposure to phosphine
N=50 fruits at the beginning of the study. 4.6.4.6 Activity 5: Effectiveness of sticky traps to assess gall midge population over a six-month period 4.6.4.6.1 Objectives
4.6.4.6.2 Methodology Sticky traps of three colours - red, green and yellow were evaluated at the CARDI field station (UWI, Mona Campus) during the period September-December, 1998. The red and green traps were constructed from cartridge paper covered with plastic and coated with an adhesive (Tangle foot). Yellow traps were commercially purchased and consisted of waxed cardboard on which an adhesive was applied. Traps were suspended at the height of the plant canopy with bamboo sticks. The field was divided into 6 blocks and traps were placed
in a RCB design such that, there were 2 traps of each colour present in
each block (n=54, total plant population= 336). The number of midges trapped
was recorded weekly. 4.6.4.6.3 Results and Discussion Gall midge adults were caught on traps all colours. The yellow trap caught the largest number of adults when compared to red and green traps; the average per trap was 0.5, 0.10, and 0.16 adults for the yellow, red and green traps respectively (Figure 2). Given the high larval infestation observed during the study and the low number of adult midges caught, the traps may be useful as detection tool vs a monitoring tool in .the IPM strategy being developed. The study is being continued so that more precise conclusion can be made. In addition, the repeat study will also attempt to determine the optimal trap height required.
Figure 10: Mean weekly trap catch of gall midge adults by traps of different colours. |
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