Evaluation of Beauveria bassiana (Ascomycota: Hypocreales) as a control of the coffee berry borer Hypothenemus hampei (Coleoptera: Curculionidae: Scolytinae) emerging from fallen,infested coffee berries on the ground

The effects of Beauveria bassiana strains on coffee berry borers (CBB), which emerge from infested berries left on soil, and its impact on the infestation of coffee berries on tree branches were evaluated at two Experimental Stations (Naranjal-Caldas and Paraguaicito-Quindio) in the Colombian coffee zone. Using a completely randomized design with 10 repetitions, 50 coffee berries artificially infested with CBB were placed on the base of a coffee tree. Four treatments including B. bassiana strain Bb9205, a mixture of Cenicafé strains (Bb9001, Bb9024 and Bb9119), a commercial formulation of B. bassiana and a control (water) were sprayed with 1×10⁹ conidia per tree. After 30 days, all fungal strains lowered the infestation levels of the coffee berries on the trees at both locations. The mixture of Cenicafé strains decreased the tree infestation between 50 and 30% at both locations. In the berries dissected from each treated tree, insect mortality was about 40% at both locations compared to 15% in the control. B. bassiana strains also decreased the insect population inside the newly infested berries on the trees by 55–75%. The mixture of Cenicafé strains was the most effective for decreasing insect populations. B. bassiana significantly decreased CBB populations that emerged from fallen, infested, coffee berries and reduced future insect generations.     

Forest association and phenology of wild coffee in Kibale National Park, Uganda

A study on the forest association and phenology of wild coffee ( Coffea canephora Pierre) was conducted in Kibale forest, Uganda. Nested quadrats were used to enumerate tree species, including coffee and herbaceous plants associated with forest and coffee stands. A total of 150 coffee trees was marked along transects and monthly scans carried out to score for fruits, flowers, leaves and leaf insect damage. Pre- and post-dispersal predation levels and coffee yield estimates were made by examining fruits from trees, forest floor and seasonal fruit falls into demarcated plots. In the forest, wild coffee stands are associated with low-quality forest types in terms of timber species (about 10.5 canopy species/study site) and low stocking densities of trees ≥ 50 cm d.b.h. (average 38 trees ha⁻¹ for each site) and poor forest regeneration. In the forest, wild coffee reproductive phases overlap with ripening, coinciding with flower bud and flower production. The variable peak ripening season falls between November and April. The wild coffee yields are generally low (average of 3.5 intact fruits 16 m⁻² month⁻¹), with low insect fruit/seed damage (4–19%) but high levels of wastage due to monkeys, bats and birds.     

Altitude and coffee production systems influence extent of infestation and bean damage by the coffee berry borer

The coffee berry borer (CBB), Hypothenemus hampei Ferrari (Coleoptera: Curculionidae: Scolytinae), is one of the major insect pests of coffee worldwide. The present study was designed to assess the level of infestation of coffee berries at different developmental stages across different altitudes and coffee management systems. The experiment was carried out at three locations in southwestern Ethiopia under two coffee management systems and four coffee berry development stages with three replications. Results of the study showed significantly highest proportion of damaged berries (37.5%), number of holes per berry (10.88) and number of adult CBB per berry (7.55) on dried leftover berries at low-altitude study sites. On the other hand, the lowest mean percent damaged berries, number of holes per berry and number of adults were recorded at mid- and high-altitude study sites. The study also showed that, CBB caused significantly highest damage in plantation coffee management system than garden coffee. Results of this study highlight proper harvesting at red ripe stage in order to minimise incidence of CBB. It is also important to design integrated management strategies to mitigate CBB damage especially in lowland plantation coffee production systems.     

Bacillus thuringiensis and neem seed oil (Azadirachta indica) effects on the potato tuber moth Phthorimaea operculella zeller in the field and stores

A comparative evaluation for the efficacy of Bacillus thuringiensis and neem seed oil on Phthorimaea operculella has been carried out in the field and store. These two preparations were almost equally effective on the potato tuber moth infestation. The percentage of infestation was reduced through successive application of either preparations in the field up to harvest. No synergism was observed upon using combination of the two preparations. In the store, neem seed oil (500 ppm) was highly protective and was as effective as sevin. A combination of both neem and B.t. (Delfin) significantly protects the tubers. This suggests the possible use of either neem seed oil or B.t. in combating the insect pest in the field or during storage.     

Fruit and seed ecology of wild robusta coffee (Coffea canephora Froehner) in Kibale National Park, Uganda

Coffee fruit production, frugivorous activities and seed longevity were investigated during two seasons. The average densities of fruiting coffee trees during the first sampling period ranged from four to seven per 25 m² and during the second sampling period, four fruiting trees per 25 m² were estimated. Fruiting coffee trees were significantly less than the non-fruiting trees ( P < 0.05, t -test). Periods of maximum coffee fruit fall coincided with those of lowest rainfall. Coffee fruit yield per tree from ground collections was 7–40 m⁻² in 1992 and 16–38 m⁻² in 1993/1994. Split coffee berries ranged between 71.7% and 83.6% of all fruits collected from the forest floor in the 1993/94 sampling period. Coffee seeds collected from the forest floor were mostly undamaged. Black and white colobus and redtail monkeys were observed to feed on ripe coffee fruits but did not crush the seeds. Coffee seed viability declined rapidly during storage. Seeds left on the forest floor survived longest, those stored under laboratory conditions lost viability fastest, and those in cold storage showed intermediate longevity.     

Mediterranean fruit fly (Dipt., Tephritidae) suppression in persimmon through bait sprays in adjacent coffee plantings*

Abstract: Oriental persimmon, Diospyros kaki L., in Upper Kula on the island of Maui (Hawaii) is attacked by the Mediterranean fruit fly, Ceratitis capitata (Wiedemann). Recent suppression trials using mass trapping with a synthetic food‐based bait, initiated in alternate host crops before the start of persimmon season, had shown promise as a means of reducing C. capitata population levels. However, this did not adequately suppress C. capitata population where there were adjacent plantings of coffee, Coffea arabica L., a favoured alternate host, which bears fruits before and during the persimmon season. To improve C. capitata population suppression, we applied a spinosad‐based bait spray to coffee plants, starting before persimmon fruits became susceptible to oviposition by the Mediterranean fruit fly. The bait spray suppressed the C. capitata population and led to reduced infestation of both coffee cherries and persimmon fruits. Percentage parasitization of C. capitata in coffee cherries by established biological control agents, primarily Fopius arisanus (Sonan), was not significantly different in unsprayed vs. sprayed plots even after 11 weekly sprays. These results suggest that mass trapping, combined with spinosad‐based bait sprays, are control components that are compatible with biological control and can be combined in an integrated pest management system for C. capitata.     

Combination of edible vegetable oil and artificial fruit to reduce Bactrocera dorsalis oviposition in chilli fruits

Bactrocera dorsalis (Hendel) is a major pest of a wide variety of fruits and vegetables. This study aimed to evaluate the potency of combining edible vegetable oil application and artificial fruit provision to reduce the oviposition of B. dorsalis in chilli fruits. Experiments were conducted in laboratory using a 20‐L plastic container provided with chilli fruits and in semi field using a fruit‐bearing chilli plant caged with insect screen. The laboratory test revealed that the combination of coconut oil application and artificial fruit provision significantly reduced fruit fly visits, eggs laid and the number of infested chilli fruits no matter when the chilli fruits were without prepuncture or with prepuncture. Further study using a caged chilli plant also found that this combination had significant effects on fruit fly visits and infestation in chilli fruits. These results provide an indication that coconut oil and artificial fruit can work together to reduce fruit fly attacks on chilli fruits. Combining the use of coconut oil and artificial fruit is likely to create an integrated behavioural manipulation (push and pull) of female B. dorsalis that lead to a much lower fruit fly infestation in chilli fruits.     

Status of pollinators and their efficiency in coffee fruit set in a fragmented landscape mosaic in South India

The region of Kodagu, South India, comprises a fragmented landscape with a high density of remnant forest patches dispersed within a mosaic dominated by shaded coffee agro-forests. We evaluated the role of self, wind and insect pollination to Coffea canephora production in this landscape. The giant Asian honeybee, Apis dorsata, which nests in remnant forests, was the main pollinator of coffee (accounting for 58% of the floral visitors). The proportion of flowers that developed into fruits was highest when hand cross-pollinated (44%), followed by open- (insect and wind combined; 33%) and wind- (22.1%) pollination treatments. Pollination by bees therefore increases fruit production by 50% over that achieved by wind. Self-pollination (1.7%) and no pollination (1%) treatments produced very low fruit set, emphasizing the importance of cross-pollination in C. canephora. Unlike measures of pollination success, initial fruit set (five weeks after flowering) proved an unreliable proxy for final fruit set. Size of adjoining forest fragments (mostly 0.3–20 ha, with a few exceeding 200 ha) positively influenced pollinator visitation to coffee flowers, but distance to such fragments had no influence on pollination. This study demonstrates the importance of cross-pollination for crop production in C. canephora, the important contribution that pollinating insects make to coffee production, and the benefits of relatively large forest fragments within the landscape mosaic to support insect pollinators of coffee. A comparison of pollinator composition to that of 100 years ago indicated that coffee pollination services remained intact despite changes in pollinator community composition.     

Evaluation of potential entomopathogenic fungus,Beauveria bassiana,for controlling the coffee berry borer Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae) in Taiwan

Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae), a coffee berry borer (CBB), is a serious pest of coffee fruits and causes economic losses in the coffee industry. With the concerns of chemical control, an alternative eco-friendly management strategy such as microbial control has emerged as the times require. Herein, a total of thirty-three fungi were isolated from CBB cadavers. Two entomopathogenic fungal isolates, NCHU-271 and NCHU-272, which showed fast insect-killing activity, were subjected to molecular identification and named “Beauveria bassiana-NCHU-271” (Bb-NCHU-271) and “Beauveria bassiana -NCHU-272” (Bb-NCHU-272). Moreover, a virulence test of Bb-NCHU-271 and Bb-NCHU-272 against CBBs was also performed. Both Bb-NCHU-271 and Bb-NCHU-272 caused 100% mortality at 8 days post inoculation (d.p.i.) and a LT₅₀ of Bb-NCHU-271 by spraying 10⁸ conidia/ml was less than Bb-NCHU-272. Therefore, histological evidence of Bb-NCHU-271 infected CBBs was provided to proven the infection process of B. bassiana in CBBs. Furthermore, an infestation test was performed to evaluate the differences in CBB control efficacy between the treatments of “Borers exposed to EPF first” or “Berries exposed to EPF first”. The results revealed that the “Borers exposed to EPF first” of Bb-NCHU-272 caused significantly lower survival rates and higher mycosis rates than those of Bb-NCHU-271. Only slight control effects of Bb-NCHU-271 and Bb-NCHU-272 were also observed in the “Berries exposed to EPF” treatment. In conclusion, Bb-NCHU-271 and −272 showed controlling ability to the CBBs either before or after CBB infestation into coffee berries, while application of EPFs before the CBBs bored into coffee fruits could enhance the control effect.     

Abundance of Coffee berry borer in feral,abandoned and managed coffee on Hawaii Island

Coffee berry borer (Hypothenemus hampei Ferrari), the most damaging insect pest of coffee worldwide, was first detected on Hawaii Island in 2010. Poorly managed, abandoned and feral coffee sites on the island have since been thought to harbour coffee berry borer (CBB) populations, which then negatively impact neighbouring coffee farms. In the present study, we sought to quantify CBB abundance in these sites, which vary in management intensity and vegetation structure and diversity. We collected data on trap catch as a measure of CBB flight activity, fruit production and fruit infestation by CBB in eight well-managed farms and sites that were either poorly managed, abandoned or feral (wild) coffee. Sites were sampled bi-weekly over a period of 2 years from 2016 to 2017. We found that CBB flight activity was significantly higher in poorly managed sites relative to abandoned and feral sites, but was not significantly different from well-managed sites. Coffee production in well-managed farms was significantly higher than in abandoned and feral sites, but was not significantly different from poorly managed farms. CBB infestation in poorly managed sites was significantly higher than that observed in well-managed, abandoned and feral sites. We estimated an average load of 11–25 CBB per branch at poorly managed sites, compared to 3–9 per branch at well-managed sites, 1–16 per branch at abandoned sites and 1–3 per branch at feral sites. Our findings suggest that poorly managed sites should be prioritized for implementation of CBB control measures as part of a landscape-level integrated pest management (IPM) programme.     

Field evaluation of neem and canola oil for the selective control of the honey bee (Hymenoptera: Apidae) mite parasites Varroa jacobsoni (Acari: Varroidae) and Acarapis woodi (Acari: Tarsonemidae)

Neem oil, neem extract (neem-aza), and canola oil were evaluated for the management of the honey bee mite parasites Varroa jacobsoni (Oudemans) and Acarapis woodi (Rennie) in field experiments. Spraying neem oil on bees was more effective at controlling V. jacobsoni than feeding oil in a sucrose-based matrix (patty), feeding neem-aza in syrup, or spraying canola oil. Neem oil sprays also protected susceptible bees from A. woodi infestation. Only neem oil provided V. jacobsoni control comparable to the known varroacide formic acid, but it was not as effective as the synthetic product Apistan (tau-fluvalinate). Neem oil was effective only when sprayed six times at 4-d intervals and not when applied three times at 8-d intervals. Neem oil spray treatments had no effect on adult honey bee populations, but treatments reduced the amount of sealed brood in colonies by 50% and caused queen loss at higher doses. Taken together, the results suggest that neem and canola oil show some promise for managing honey bee parasitic mites, but the negative effects of treatments to colonies and the lower efficacy against V. jacobsoni compared with synthetic acaricides may limit their usefulness to beekeepers.     

Oviposition deterrents for the Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae) from fly faeces extracts

After oviposition, females of the Mediterranean fruit fly Ceratitis capitata Wiedemann deposit a host-marking pheromone on the fruit surface that deters oviposition by conspecifics. Methanolic extracts of fruit fly faeces elicit a similar deterrent effect. The results of laboratory and field experiments using raw methanolic extracts of C. capitata faeces as an oviposition deterrent are reported. Laboratory bioassays revealed a significant positive relationship between concentration of faeces and the inhibition of oviposition responses by C. capitata. Treatment of halves of coffee bushes with methanolic extracts containing 0.1, 1.0 and 10 mg faeces ml(-1) resulted in a significant reduction of infestation only at the highest concentration (P=0.03). Treatment of blocks of coffee bushes with an extract of 10 mg faeces ml(-1) resulted in an 84% reduction in infestation by C. capitata in sprayed plants and a 56% reduction in adjacent untreated coffee bushes surrounding treated plots, probably due to the deterrent effect of host-marking pheromone on fly oviposition. We conclude that faeces contain oviposition deterrent substances that effectively reduce fruit infestations by C. capitata, suggesting a clear potential for the use of this infochemical in integrated management programmes targeted at this pest.     

Coffee volatiles induced after mechanical injury and beetle herbivory attract the coffee berry borer and two of its parasitoids

The coffee berry borer (CBB), Hypothenemus hampei (Ferrari), is the most important insect pest of coffee worldwide. In this study, we used headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry to sample and identify volatile compounds from Robusta coffee berries, Coffea canephora Pierre ex Froehner, infested with CBB and with mechanical damage. Furthermore, we evaluated the behavioral responses of the CBB and two of its parasitoids, Prorops nasuta Waterstone and Phymastichus coffea LaSalle, to three selected coffee volatile compounds in a Y-tube olfactometer. We found in the effluvia of red coffee berry compounds not previously reported for this coffee species. Our results show that Robusta coffee berries release induced volatiles either by insect herbivory or by mechanical damage. Small amount of butyl acetate, unknown compound 2, α-longipinene, longiborneol and longiborneol acetate are produced only in infested coffee berries fruits. Quantitatively, nine compounds account for the difference between healthy berries, infested, or mechanically damaged berries. Trans-ocimene, 4,8-dimethyl-3,7-nonadien-2-ol, α-copaene and kaurene increased amount levels in infested berries, while amount of methyl salicylate and linalool increased in mechanically damaged coffee berries. The olfactometric bioassays showed that CBB females and its two parasitoids were attracted to methyl salicylate. In addition, H. hampei and P. nasuta were attracted to linalool, and P. nasuta and P. coffea were attracted to trans-ocimene.     

Interspecific competition between Cephalonomia stephanoderis and Prorops nasuta (Hym.,Bethylidae), parasitoids of the coffee berry borer, Hypothenemus hampei (Col., Scolytidae)

The competition between Cephalonomia stephanoderis and Prorops nasuta was studied in the laboratory, using coffee fruits infested with the host of these parasitoids, the coffee berry borer Hypothenemus hampei . Experiments were performed under different conditions, using: (a) three temperatures; (b) five densities of infested coffee fruits; and (c) introducing the parasitoids at different times. The effect of competition was determined according to the production of the progeny. When cultured together at the same time, C. stephanoderis produced in general, more progeny than P. nasuta under conditions of 29°C and alternating temperatures of 18–29°C. Nevertheless, there were significant differences at densities of 1 : 3, fruits : parasitoids ( F _0.05=8.9; d.f.=1, 12; P < 0.05) and 1 : 5 ( F _0.05=7.56; d.f.=1, 12; P < 0.05) at 29°C. Under alternating temperatures, there were differences at the same ratios as above in favour of C. stephanoderis , 1 : 3 ( F _0.05=20.08; d.f.=1, 12; P < 0.05) and 1 : 5 ( F _0.05=20.21; d.f.=1, 12; P < 0.05). Prorops nasuta was clearly more successful in all densities at 18°C. When C. stephanoderis was introduced 10 days before P. nasuta , the progeny production was markedly higher in eight from 10 densities at temperatures of 29°C and 18–29°C. Despite being introduced 10 days later, P. nasuta showed better performance at 18°C. When P. nasuta was introduced 10 days earlier than C. stephanoderis , there were significant differences in progeny production in favour of P. nasuta in 13 of 15 fruit densities under the three temperatures. Both parasitoids avoided ovipositing on previously parasitized hosts. Aggressive behaviour or interference was not observed when they were outside coffee fruits.     

Laboratory evaluation of Melia azedarach L. and Eucalyptus globulus Labill. Extracts in order to control Ocneridia volxemi Bolivar (Orthoptera, Pamphaginae) hoppers

This study was carried out to evaluate the effect of Melia azedarach L. (Meliaceae) dry fruit extracts (oil and water) and Eucalyptus globulus Labill. (Myrtaceae) dry leaves extracts (water) on Oneridia volxemi hoppers (fifth-instar) feeding on cereals leaves (Triticum durum) under laboratory conditions. Larva feeding reduced and mortality was significatly (p < 0.05) on cereals leaves sprayed with three concentrations 0, 5, 1 and 2% of oil extracted from Melia azederach. In addition, O. volxemi feeding and mortality was significantly (p < 0.05) on cereals leaves sprayed with two concentrations 50 g/l and 80 g/l of water extracts from Melia azedarach dry fruits soaked for 24 hours. the water extract solution of 80 g/l significantly reduced feeding than the other concentrations 50 and 25 g/l. This study showed also the water extract solution from Eucalyptus globulus dry leaves reduced also feeding and induced the mortality of O. volxemi but not better than Melia azedarach dry fruit extracts water at the same concentration (80 g/l). The aim of this study is in an integrated management program for control of O.     

Evaluation of three aqueous plant extracts and Lamdacot in controlling eggplant fruit borer (Daraba laisalis Wlk.) (Lepidoptera: Pyralidae) in north-eastern Nigeria

Field experiments carried out in Dadinkowa, Gombe State, Nigeria, during 2007 and 2008 cropping seasons evaluated the efficacy of three aqueous plant extracts namely neem (Azadirachta indica A.H.L. Juss.), bitter melon (Momordica balsamina Linn.) and siam weed (Chromolaena odorota (L.) King and Robinson) compared to a conventional insecticide, Lamdacot 500EC, in managing fruit borer (Daraba laisalis Wlk.) attack of eggplants in north-eastern Nigeria. The experiments were laid out in a randomised complete block design replicated four times including controls. The results showed that the application of aqueous extracts (5% w/v concentration) of A. indica and M. balsamina at one-week interval during the fruiting stage was effective and at par with the conventional insecticide, Lamdacot, in reducing eggplant fruit borer infestation and fruit damage, as well as the resulting increase in fruit yield. Farmers can therefore adopt the practice of applying 5% w/v concentration of the above aqueous plant extracts at weekly intervals to control fruit borer attack of eggplants in the north-eastern region of Nigeria.     

Use of plant extracts and biocontrol agents for the management of brown spot disease in rice

Fifty plant extracts, four oil cakes and eight antagonistic organisms were tested against Bipolaris oryzae (Cochliobolus miyabeanus), the causal agent of brown spot disease of rice. In vitro studies indicated that two leaf extracts, Nerium oleander and Pithecolobium dulce exerted the higher percent inhibition to mycelial growth (77.4, 75.1%) and spore germination (80.3, 80.0%) of B. oryzae. Among the four oil cake extracts tested in vitro against B. oryzae, neem cake extract showed the maximum inhibition percent to mycelial growth (80.18%) and spore germination (81.13%) of the pathogen followed by mahua cake extract, castor and gingelly cake extract. Trichoderma viride (Tv2) was significantly effective in inhibiting the mycelial growth (62.92%) and spore germination (77.03%) of the pathogen followed by Trichoderma harzianum (Th5) and Trichoderma reesei (Tr3). The promising leaf extracts, oil cake extracts and antagonistic microorganisms were further evaluated for their efficacies in disease management under glasshouse and field conditions. In glasshouse studies, post-infectional spraying of rice plants with neem cake extract, N. oleander leaf extract and T. viride (Tv2) was significantly effective in reducing the incidence of brown spot of rice by 66, 52 and 45 percent respectively. Two rounds of spraying of rice plants with neem cake extract, N. oleander leaf extract and T. viride (Tv2) in the field at initial appearance of disease and 15 days later reduced the incidence of brown spot (70, 53 and 48% disease reduction respectively) and increased the yield by 23, 18 and 15 percent respectively.     

Comparative laboratory toxicity of neem pesticides to honey bees (Hymenoptera: Apidae), their mite parasites Varroa jacobsoni (Acari: Varroidae) and Acarapis woodi (Acari: Tarsonemidae), and brood pathogens Paenibacillus larvae and Ascophaera apis

Laboratory bioassays were conducted to evaluate neem oil and neem extract for the management of key honey bee (Apis mellifera L.) pests. Neem pesticides inhibited the growth of Paenibacillus larvae (Ash, Priest & Collins) in vitro but had no effect on the growth of Ascophaera apis (Olive & Spiltoir). Azadirachtin-rich extract (neem-aza) was 10 times more potent than crude neem oil (neem oil) against P. larvae suggesting that azadirachtin is a main antibiotic component in neem. Neem-aza, however, was ineffective at controlling the honey bee mite parasites Varroa jacobsoni (Ouduemans) and Acarapis woodi (Rennie). Honey bees also were deterred from feeding on sucrose syrup containing > 0.01 mg/ml of neem-aza. However, neem oil applied topically to infested bees in the laboratory proved highly effective against both mite species. Approximately 50-90% V. jacobsoni mortality was observed 48 h after treatment with associated bee mortality lower than 10%. Although topically applied neem oil did not result in direct A. woodi mortality, it offered significant protection of bees from infestation by A. woodi. Other vegetable and petroleum-based oils also offered selective control of honey bee mites, suggesting neem oil has both a physical and a toxicological mode of action. Although oils are not as selective as the V. jacobsoni acaricide tau-fluvalinate, they nonetheless hold promise for the simultaneous management of several honey bee pests.     

Efficacy of neem pesticides on whorl larva,stem-borer and panicle insect pests of sorghum in Nigeria

Two field trials were conducted from 2003 to 2005 on the effects of neem pesticides on whorl larva, stem-borer and panicle pests of sorghum. In the first trial (2003–2004) the effect of neem seed granules (NSG) and carbofuran (furadan 3G®) inserted into the sorghum whorl at 30, 40 and 50 days after sowing (DAS) were tested on whorl larva, stem borer and grain yield. Results showed that NSG and carbofuran significantly (P ≤ 0.01) reduced whorl larva feeding, leaf puncturing and chaffy panicle, and significantly (P ≤ 0.01) increased grain yield compared with untreated check. In the second trial, (2004–2005), aqueous neem seed extract (ANSE), neem seed oil (NSO) and deltamethrin (Decis 12 EC®) were sprayed at anthesis and grain filling stages. Results also showed that the three pesticides significantly (P ≤ 0.01) reduced insect damage and also significantly (P ≤ 0.01) increased grain yield by 28.3% (deltamethrin), 19.4% (NSO) and 17.9% (ANSE) above the yield of check. It is suggested that neem pesticides may be suitable as alternatives to synthetic pesticides for the management of sorghum whorl larva, stem borers and panicle insect pests in the Nigerian Sudan savannah.     

Branch growth dynamics,photosynthesis, yield and bean size distribution in response to fruit load manipulation in coffee trees

Key message

The study unraveled the dynamics of mechanisms causing biennality in coffee, its consequences for competition for carbon and nitrogen and suggests means of adequately managing the problem.

Abstract

Imbalance in fruit load and branch growth plays a role in the occurrence of biennial bean production patterns in coffee (Coffea arabica L.). Effects of fruit load manipulations were studied in two field experiments in the Jimma region, Ethiopia, over two consecutive years. Treatments consisted of reducing fruit loads in the pinhead stage to 25, 50, 75 % and controls keeping 100 % of the fruits per tree (treatments coded T25 through T100). Treatments were applied in the first year only. Branch growth and the formation of new leaves, drop of old leaves, light saturated rate of leaf photosynthesis (A _max), nitrogen content of leaves on selected branches, as well yield and bean characteristics were evaluated throughout the experimental period. The study revealed that branch growth, and leaf N content per unit leaf area, N _a, were inversely associated with fruit load, whereas loss of basal leaves on branches increased with fruit load and over time. A _max was strongly and linearly associated with N _a and declined with increase in fruit load. In the year of treatment green bean yield increased with fruit load, but in the second year the reverse was true. On aggregate over 2 years, treatment T25 and T50 out yielded treatments T75 and T100. Fruit thinning shifted the bean size distribution to larger sizes. In conclusion, fruit thinning modulated the balance between branch growth and fruit development. Thus enhanced branch growth, improved bean size and stabilized yield over years.