Stalk Borer Research Articles

Determining the economic threshold for the sugarcane stalk borer (Diatraea spp.) in the Córdoba-Golfo region, Veracruz, Mexico

Objective: To determine the economic threshold for Diatraea spp. in the Córdoba-Golfo sugarcane growing region in Veracruz, Mexico. Design/Methodology/Approach: During the 2020-2021 production cycle, we established 21 sampling plots to measure damage percentage due to borer larvae in sugarcane stalks. Based on these measurements, we calculated the economic damage level (EDL) and the economic threshold (ET) by regions and subregions. Results: The most affected subregion was Yanga, with an average annual damage of more than 5 % and a real economic threshold of 1.36. The average ET in the Córdoba-Golfo region was 2.76, which indicates that applying control strategies for Diatraea spp. enables the regulation of insect populations. Study limitations/Implications: Strategies to obtain reality-driven diagnoses are still necessary to design and apply assertive management procedures to control stalk borer populations in the field. Findings/Conclusions: We posit a suitably calculated ET for each studied subregion, considering updated parameters that include real crop losses per zone (field performance). This can provide the basis for a course of action with an effective management that will, in turn, increase field performance and sugarcane juice quality.

First report of Diatraea impersonatella (Lepidoptera: Crambidae) on sugarcane (Saccharum officinarum L.) in Honduras

Abstract This study is the first report of the stalk borer Diatraea impersonatella (Walker) on sugarcane in Honduras. A total of 167 larvae were collected from sugarcane crops in the Department Francisco Morazán, Municipality Villa de San Francisco, Honduras, during November 2022 to January 2023. The larval specimens were reared with the objective of obtaining adults for the morphological identification of the species through the inspection of male genitalia.

Field infestation of the invasive fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) on maize in Southern Ethiopia

The biggest obstacle to Ethiopia's maize production is the fall armyworm (FAW), Spodoptera frugiperda. Since its recent introduction, the pest has assumed a key pest status displacing most other stalk borer insects known to attack maize in the country. This study was carried out to assess the infestation of FAW on maize, identify associated natural enemies, and determined the geographic distribution of the pest in southern Ethiopia. Infestation by FAW was encountered in most surveyed areas. The earwig, Doru luteipes (Scudder) was frequently found preying on larvae of FAW while the larvae of Chrysoperla rufilabris (Burmeister) were observed feeding on FAW egg masses. Megaselia scalaris (Loew) and Palexorista zonata (Curran), two parasitoids of FAW, were recovered from FAW larvae. The entomopathogenic fungus, Beauveria bassiana, was isolated from the cadaver of FAW larvae. Modeling the distribution of FAW revealed that there are many suitable places in southern Ethiopia, with low-lying plain lands having the greatest potential for pest invasion. With AUC values above 0.9, the MaxEnt models demonstrated great prediction accuracy. Precipitation in the driest month (27.3%) and precipitation in the coldest quarter (25.4%), accounted for more than half of the variance in the pest's potential distribution. The findings of this study have contributed to a greater understanding of field infestation of FAW and associated natural enemies. The species distribution model result constituted a crucial point in providing the rationale for devising management strategy by taking into account a specified area susceptible to enhance invasion risk by FAW.

Management of the Yellow Corn Stem Borer, Sesamia cretica Led. Using Some Pesticides and Their Alternatives and Their Effect on Production Constituents of Yellow Corn Crop Zea mays in Kirkuk Governorate

Our study, the spring cultivar of the yellow corn crop was adopted in the experimental land, the aim of which was to know the best materials used in managing the corn stalk borer insect. Environmentally friendly materials were used (ash - remnants of burnt materials, in addition to table salt). In addition to our use of effective and approved pesticides in the control of stem borer in a field experiment to see the effect of the materials used on insect infestation rates It also had an effect on the killing rate of corn stalk borer larvae achieved by spraying with the experimental materials, in addition to its effect on the height of infected plants compared to the control treatmen Field surveys were conducted to find out the extent of infection with this insect in the center of Kirkuk Governorate. The experiment was repeated for the fall season 2022, with field surveys conducted for the purpose of confirming the economic importance of the insect.t. The results indicated the spread of the corn stalk borer insect in all corn-growing areas, for which tables were prepared regarding the infection rate. In the autumn season 2021 in Kirkuk Governorate. The results indicated that there was a clear effect of the materials used in the treatments, with a relative superiority of the ash and table salt treatments over the pesticide treatments (Diazinon 10% granular and Aktara EC 25).

Biological and behavioural responses of the sugarcane borer parasitoid Tetrastichus howardi to insecticides

AbstractThe pupal parasitoid Tetrastichus howardi (Olliff) (Hymenoptera: Eulophidae) parasitizes pupae of sugarcane stalk borers inside the stalk. Parasitoids currently used for applied biological control of sugarcane stalk borers target eggs and larvae, and T. howardi will add mortality to the pest stage with high survival. Nevertheless, insecticide applications required to control sugarcane borers and other sugarcane pests can affect T. howardi parasitism. Survival, walking, evasion and parasitism of T. howardi females were evaluated in response to the dry residue of insecticides from different chemical groups: chlorantraniliprole, bifenthrin, spinetoram, ethiprole, fipronil and thiamethoxam. Females of the parasitoid were confined on sugarcane leaves containing residues of the insecticides at 2, 24, 48, 72 and 96 h intervals after application, and survival monitored during the 96‐h period with subsequent determination of parasitism in the laboratory. Furthermore, female walking behaviour was observed individually using half‐treated arenas with insecticides. Chlorantraniliprole was compatible with T. howardi irrespective of residual intervals and studied variables. Other tested insecticides did not allow parasitoid survival up to 96 h of confinement on dry residues and, consequently, parasitism. Locomotory activity indicated that parasitoid females might avoid residues of spinetoram and ethiprole. Females were released in cages containing spinetoram and ethiprole‐treated sugarcane plants with the chance to move to untreated plants, parasitized pupae placed on either treated or untreated plants within a 24 h exposure period, which resulted in offspring production. Females observed for 10 min for walking behaviour in a half‐treated arena with chlorantraniliprole, ethiprole, fipronil, spinetoram, bifenthrin or thiamethoxam exhibited 100%, 73.3%, 70%, 66.7%, 10% and 0% survival after 24 h, respectively. Chlorantraniliprole was compatible with T. howardi through the bioassays conducted, and parasitoids showed the ability to parasitize their hosts on spinetoram‐ and ethiprole‐treated plants moving away from the treated environment.

Effect Infestation by Sesamia cretica L. Insect in some Characteristics of Growth for Varieties of Yellow Corn

This observe changed into carried out in the fields of Al-Hawija location of Kirkuk Governorate for the reason of reading the assessment of a few sorts of yellow corn for contamination through the corn stalk insect (Sesamia cretica L) and the impact of the insect infestation on a few traits and boom of yield of a few yellow corn cultivars. The maximum contamination fee of the ZOAN cultivar changed into 7.50% in comparison to the bottom contamination fee with inside the Samuray 34 cultivar of 0.50 % after a duration of 20 days of germination, however after forty days the contamination fee changed into maximum at the ZOAN cultivar 45% and for the nearby range 37.30% in comparison to the Samuray 34 cultivar 4% only, and after 60 days, the contamination fee changed into 25.75% for the ZOAN variety and for the nearby 19%, in comparison to 4.70% for the Samuray 34 variety. The number of caterpillars for each plant ranged between (0.30-2.70) for each plant for the studied cultivars. As for the average number of shoots for each plant, it ranged between (0.30-3) for each plant for the studied cultivars, as it was the lowest for the Samuray 34 cultivar and the highest for Sweetened (local) cultivar. Sweetened (local) cultivar, Wazawan, recorded the highest percentage of shoot lengths for each plant, as it was 9.30% and 7.50%, respectively, compared with the rest of the studied cultivars, as it was the lowest for the Samuray 34 cultivar, 1.33% of the plant, and for the Konstiz cultivar 3.60%, and for the Jameson cultivar 6%, while there were clear significant differences. In the percentage of shortening in the number of seeds and the values of loss in the weight of 100 grains, as well as the percentage of shortening in the crop, as the percentage of loss in the number of grains for the Samuray 34 variety was 12.33%, and the highest was for the Zawan variety by 18%, compared to the percentage of loss in Sweetened (local) variety amounted to 17.30%. The Samuray 34 cultivar recorded the lowest percentage of shortening in the weight of 100 grains, as it was 6% compared to the ZOAN cultivar, 8.60% compared to the rest of the studied cultivars, which was reflected in the percentage of loss in the total crop, as the percentages ranged between (19-24) %, as the Samuray 34 cultivar recorded the lowest percentage. It amounted to 19%, compared to 22.67% for the Zawan variety, and for Sweetened (local) 24%, compared to the rest of the maize varieties. The best cultivar was the Samuray 34 cultivar for use in breeding programs for corn stalk borer control.

Circadian clock genes and photoperiodic diapause in the moth Sesamia nonagrioides.

Insects, like most organisms, have an internal circadian clock that oscillates with a daily rhythmicity, and a timing mechanism (photoperiodic clock) that mediates seasonal events, including diapause. It has been argued that there is a connection between the two clocks. The Mediterranean corn stalk borer moth, Sesamia nonagrioides, undergoes facultative diapause governed by photoperiod. To obtain clues to the link between the molecular mechanism of circadian and photoperiod clocks, we cloned and investigated the expression profiles of the clock genes Snper, Sntim, Sncyc and Sncry1 in the aforementioned moth species. Our previous results suggested that these genes might be implicated in the regulation of the diapause programming in S. nonagrioides. Here we studied the expression patterns of these four clock genes in larvae reared under abnormal non-24 h light-dark cycles (L10:D62 and L10:D14:L10:D62) in order to assess whether disruption of circadian clock would have any effect in the photoperiodic regulation of diapause. In the L10:D14:L10:D62 cycle abnormal expression patterns of the Sntim/Sncry1 and Snper/Sncyc, pairs were found, compared to normal 24 h light-dark photoperiods suggesting that individual clock genes are acting independently in the molecular diapause program of S. nonagrioides. Photoperiod therefore appears to be the crucial signal for the regulation of these four genes.

Multi-seasonal modelling of the African maize stalk borer with assessment of crop residue management

Maize, also known as corn, is one of the most popular food in the world. Managing its Lepidoptera pests is a big deal as the larvae, which cause severe damages, develop inside maize stalks and ears. The most popular means of controlling insect pests remain chemical, but agricultural practices as the management of crop residues have been proven efficient. In this paper, we analyze the effect of the Maize Stalk Borer (MSB) Busseola fusca on maize crops and the efficiency of residue management over several cropping seasons. More precisely, we build two multi-seasonal mathematical models for the dynamics of MSB interacting with maize tissues. The models account for two types of residue management: either plant residues are burned after harvest or, are buried in the soil at the end of the cropping season to reduce pest reservoir for the following cropping seasons. A qualitative analysis of the models is carried out including the computation of a pest-free solution. Moreover, for each model, we compute the ecological threshold, also known as the basic reproduction number, that shapes the stability of the pest-free solution. To characterize the impact of parameter variations on the state variables of the models, we carry out a sensitivity analysis. The sensitivity analysis points out the leading role of the plant infestation rate and the senescence rate of crop residues on model outputs. In addition, numerical simulations are presented to illustrate our theoretical results and support the discussion. Notably, we found that the basic reproduction numbers have a linear relationship with the proportion of immature pests destroyed at the end of cropping seasons. Therefore, advocating management policies that lead to an increase in the proportion of immature pests destroyed at the end of cropping seasons could be helpful to control the dynamics of MSB.

Field Control of Maize Borers Using Aqueous Seed Extracts of Thevetia Peruviana (Pers.) K. Schum

Aims: In order to find an alternative to chemical control, the insecticidal potential of aqueous extracts of Thevetia peruviana seeds formulated at 16.66 g/l were tested in the field on the maize stalk borer species.
 Study Design:  The factorial design in subdivided plots or "split-plot" with four replicates and two factors studies was used on an area of 250 m2.
 Place and Duration of Study: The experiment was carried out in a field located in the city of Yaounde, Cameroon where cassava was grown beforehand, between July and October 2021.
 Methodology: The extracts at 250 g per 15 l of water were tested against a synthetic insecticide Cypercal at 37.5 ml per 5 l of water and an absolute control (untreated) in a four replicate split-plot device. Two maize varieties (V1: CMS 8704; V2: local) and three treatments (T1: control; T2: T. peruviana seed extract; T3: Cypercal 12 EC) were used. The aqueous extract of T. peruviana was applied by spraying on stems, leaves and leaf cones from 5th to 9th weeks after sowing (SAS). Data were recorded on growth parameters, stem borer density, and maize grain yield.
 Results: The results show that the application of the treatments resulted in a good development of the growth parameters in the two maize varieties used. Two species of borer Busseola fusca and Sesamia calamistis belonging to the order Lepidoptera were identified. The density of maize stalk borers was significantly reduced (T2: 3 borers) in the subplots treated with aqueous extracts compared to the control (T1: 10 borers). Treatment T2 (2.05 t/ha) gave higher grain yield than the control (1.41 t/ha).
 Conclusion: The aqueous extracts of T. peruviana seeds having thus shown a strong insect repellent potential in the field can therefore be integrated into the framework of biological control that protects the environment and human health.

Growth, Yield, Quality and Insect-Pests in Sugarcane (Saccharum officinarum) as Affected by Differential Regimes of Irrigation and Potash under Stressed Conditions

Land productivity and quality were negatively impacted by both unbalanced fertilization and water-stressed conditions, which has arisen as an important topic of research. In the semi-arid tropics, sugarcane is the main source of sugar and ethanol; however, no potash (K) dose is recommended for the deficient sites in the region, which are further responsible for lower recovery. As a result, in order to standardize the K dose for deficient sites, present experiments carried out during plant (2019–2020) and ratoon (2020–2021) seasons. The statistical design was a split-plot design with main plot treatments comprised of I1 (irrigated) and I2 (stressed) treatments followed by K1, K2, K3, and K4 plots fertilized with 0, 40, 80, and 120 kg K2O ha−1 in subplots. Germination was reported to be 13.7, 25.0 and 32.3% higher during plant and 6.2, 17.3 and 24.4% higher during ratoon season in K2, K3, and K4 plots, respectively. Tiller’s cane−1 was recorded to be significantly affected by potash levels at 241 days after planting (DAP) and 261 and 326 days after harvesting (DAH). Periodic chlorophyll content of the sugarcane leaves was reported not to be affected by irrigation treatments except at 355 DAP and 324 and 357 DAH, where respected values were reported to be 2.06% in the plant season and 1.55 and 2.54% higher in the ratoon season in I1 plots, respectively. During plant season purity and extraction after the 10th month, respective values were reported to be 1.5% lower and 4.03% higher under I1 plots, while only Brix (%) was reported as significant and 2.42% higher in I1 plots during plant season after the 12th month. The incidence of early shoot borer (Chilo infuscatellus) and stalk borer (Chilo auricilius) was reported to be significantly higher under stressed conditions (30.4 and 21.5% lower in I1 plots) during the plant season, while early shoot borer (Chilo infuscatellus), stalk borer (Chilo auricilius) and top (Scirpophaga excerptalis) incidences were significantly lower in I1 plots to the tune of 19.6, 22 and 9.73% as compared to the I2 plots during the ratoon season. The application of 80 kg K2O ha−1 resulted in significantly higher cane yield and decreased insect-pest occurrence. Even though 120 kg K2O ha−1 promoted different plant and ratoon sugarcane characteristics, they were all statistically equivalent. In I1 plots, benefits increased from K2 to K3 plots by 26.7% during plant and 155% during ratoon seasons but decreased from K3 to K4 plots by 21.0% during plant and 26.1% ratoon seasons. In I2 plots, however, benefits from K2 to K3 plots were reported to be 72.7% during plant and 76.5% during ratoon seasons, which was reduced to 10.5% during plant and 16.7% during ratoon seasons in K4 plots. Results of a two-year study on plant and ratoon canes revealed that 80 kg K2O ha−1 at deficient sites significantly improved the performance of both plant and ratoon canes yields, sugar yields, reduced the insect-pests’ incidence, and finally the benefits of the cane farmers under both irrigation regimes.

Mortality of Diatraea saccharalis is affected by the pH values of the spore suspension of Beauveria bassiana and Metarhizium anisopliae

Fungal virulence is multifaceted and dependent on multiple factors including the pH of the spore suspension. In this study, we accessed effects of six pH values of Beauveria bassiana, and Metarhizium anisopliae medium for the growth, sporulation, and mortality on sugarcane stalk borer Diatraea saccharalis. The culture of fungi was performed onplates containing the PDA (Potato Dextrose Agar) medium. Virulence was tested in D. saccharalis larvae distributed in four replicates of 15 larvae. To evaluate the performance of the isolates, they were grown at different pH values in an artificial chitin medium to confirm the degradation capacity of the fungi at each pH. No significant difference was observed for the sporulation at pH ranged from 4 to 9 for both fungi. In the mortality assay, larval mortality was higher at pH 7 and 8 for both fungi, reaching 87% for B. bassiana and 81% for M. anisopliae.

Diatraea saccharalis (sugarcane stalk borer)

Diatraea saccharalis (sugarcane stalk borer)

Busseola fusca (African maize stalk borer)

Busseola fusca (African maize stalk borer)

Bioefficacy of plant extracts on ovicidal and oviposition deterrent against sugarcane stalk borer Chilo auricilius Dudgeon (Lepidoptera: Crambidae)

Sugarcane is a long-duration crop of 10-12 months and therefore is liable to be attacked by several insect pests. The present study aimed at assessing the ovicidal, oviposition, and larvicidal potential of two medicinal indigenous plants. Bioefficacy of Nerium indicum Mill. and Murrya koenigii L. spreng leaves extracts were tested against Chilo auricilius D. sugarcane stalk borer. The plant extracts prepared by sequential extraction method using a different solvent like, petroleum, chloroform, methanol, distilled water, and acetone at different concentrations were used. Ovipositional behavior of adult moths and the hatching percentage of the eggs were recorded using the choice method for each fraction of the plant extract. The chloroform extract of N. indicum 2.66% eggs/female and chloroform/petroleum ether extracts of M. koenigii 9.33% eggs/female were found to be effective, and reduced oviposition as compared to other extracts. At 20% concentration, petroleum ether and distilled water extracts of N. indicum 52.00 and petroleum ether extract of M. koenigii gave the lowest larval survival (74.00,72.00 and 70.00%) after 24, 48, and 72 h of exposures, respectively. However, petroleum ether extract of N. indicum at 8, 10, and 20% concentration survival of three days old eggs were registered at 60, 58, and 56%, whereas petroleum ether extract of M. koenigii at similar concentration recorded 77, 47, and 72% survival.

[IN1341] Stem Borers (Lepidoptera: Crambidae) in Florida Rice

Three stem borers, the sugarcane borer, Diatraea saccharalis (F.), rice stalk borer, Chilo plejadellus Zincken, and Mexican rice borer, Eoreuma loftini (Dyar), infest rice in the southern United States. They occur in Florida, with the Mexican rice borer being an invasive species recently introduced into the state. This publication briefly describes stem borers and sampling methods and reports results of the first extensive survey conducted to measure their occurrence in Florida rice.    

Potassium and Water-Deficient Conditions Influence the Growth, Yield and Quality of Ratoon Sugarcane (Saccharum officinarum L.) in a Semi-Arid Agroecosystem

Groundwater and soil potassium deficiencies are present in northern India. Sugarcane is a vital crop in the Indian Punjab; it is grown on approximately 91,000 hectares with an average yield of 80 tonnes ha−1 and a sugar recovery rate of 9.59%. The role of potassium (K) fertilizer under both sufficient and deficient irrigation in ratoon sugarcane crops is not well documented. We conducted a split-plot ratoon cane experiment during 2020–2021 at the Gurdaspur Regional Research Station of Punjab Agricultural University, India, on K-deficient soils. Main treatments were fully irrigated (I1) and water stressed (I0) conditions, with sub-treatments reflecting K fertilizer application rates of 0 (M1), 67 (M2), 133 (M3), and 200 (M4) kg K ha−1. The ratoon sugarcane performance was assessed in terms of growth, productivity, sugar quality and incidence of key insect pests. At harvest, trends in the growth and yield parameters in I1 were improved over the I0 treatment, with cane height (+12.2%), diameter (+3.3%), number of internodes (+5.4%), biomass yield (+7.6%) and cane yield (+5.9%) all higher, although little significant difference was observed between treatments. Ratoon cane yield under irrigation was 57.1 tonnes ha−1; in water-stressed conditions, it was 54.7 tonnes ha−1. In terms of sugarcane quality parameters, measured 12 months after harvesting the initial seed crop, values of Brix (+3.6%), pol (+3.9%), commercial cane sugar percentage (+4.0%) and extractable sugar percentage (+2.8%) were all higher in the irrigated treatments than the water-stressed plot. Irrigated treatments also had a significantly lower incidence of two key insect pests: top borer (Scirpophaga excerptalis) was reduced by 18.5% and stalk borer (Chilo auricilius) by 21.7%. The M3 and M4 treatments resulted in the highest cane yield and lowest incidence of insect pests compared to other K-fertilizer treatments. Economic return on K-fertilizer application increased with increasing fertilizer dosage. Under the potassium-deficient water-stressed conditions of the region of north India, a fertilizer application rate of 133 kg K ha−1 is recommended to improve ratoon sugarcane growth, yield, and quality parameters and economic returns for sugarcane farmers.

Potential of Ultrasound to Control Sesamia cretica (Lepidoptera: Noctuidae)

The pink stalk borer, Sesamia cretica Led. (Lepidoptera: Noctuidae), is one of the most important sugarcane pests in many regions of the world, causing severe damage to sugarcane every year. This insect has a specialized form of the auditory organ called the tympanal organ, and ultrasound can be employed as a potential tactic employed in physical control strategy against the pest. The present study evaluates the efficacy of ultrasound in controlling the pest in laboratory conditions. For this purpose, the repellent properties of various ultrasonic frequencies ranging from 21 to 100 kHz with 0.5 kHz intervals and wave shapes, including Sin(x), Cos(x) square, and sawtooth, were studied in choice experiments on the moths. The repellent effects of ultrasonic waves at frequencies 39.5 and 37.5 kHz were more significant than other frequencies in male and female moths, respectively. Furthermore, there was no significant difference between the repellent properties of different wave shapes. In non-choice experiments, the effects of the most repellent ultrasonic treatment, at frequency 37.5 kHz, on biological characteristics of various life stages and distribution patterns of the moths were investigated. The results showed that the ultrasonic treatment causes substantial reductions in many biological parameters of the immature life stages of pests, including longevity, weight, survival rate, and fecundity. Moreover, the pattern indicated that the moths tended to escape from the ultrasound. The findings of this study can be employed for manufacturing the ultrasonic repeller to be used in sugarcane fields.

Population Dynamics of Sugarcane Moth Borers in Indonesian Cane Fields

We conducted monthly monitoring of lepidopterous moth borers in four sugarcane fields in Java, Indonesia, from May 2009 to May 2011. Fields sampled belonged to Pesantren Baru, Jombang Baru, Gondang Baru and Subang sugar factories. Three main moth borer species were found to inflict damage to sugarcane plantations in all regions, and these are the stalk borers Chilo sacchariphagus (Bojer) and Chilo auricilius Dudgeon and the top borer Scirpophaga excerptalis (Walker). Tetramoera (Eucosma) schistaceana (Snellen) was also encountered but only caused minor damage. Borer populations increased with plant age and reached a peak around January – May in most cases, with the onset of rainfall triggering population rise. All borers coexisted in the same plant with no evidence of competition between the two stalk borers (C. sacchariphagus and C. auricilius) over their specific feeding location (internode) or between the two stalk borers and the top borer (S. excerptalis) over the same plant. This suggests that an infestation by one species does not make the plant less desirable to be colonised by another. Parasitism rates by natural enemies were very low which reflects the challenges facing biological control efforts in Java. Knowledge generated through this project will improve our understanding of borer dynamics in South East Asia and will enhance our preparedness for potential introduction by any of these pests into Australia

Yield and Quality of Ratoon Sugarcane Are Improved by Applying Potassium under Irrigation to Potassium Deficient Soils

The current study was carried out at the experimental farm of Rana Sugars Ltd., Buttar Seviyan, Amritsar, Punjab, India, to identify methods to improve the yield and quality of ratoon sugarcane in potassium-deficient soils. The treatments comprised two levels of irrigation, resulting in plants which either received sufficient water (I1) or were water-stressed (I2), and four rates of potassium (K) application: 0 (K1), 40 (K2), 80 (K3) and 120 (K4) kg K2O ha−1. The results showed that the irrigation levels did not influence crop parameters significantly, although all parameters presented higher values for I1-treated plots. Compared to the K1 (i.e., 0 kg ha−1 K fertiliser applied) treatment, the K2, K3 and K4 treatments yielded 11.16, 37.9 and 40.7%, respectively, higher millable canes and 1.25, 5.62 and 13.13% more nodes per plant, respectively. At 280 days after harvest of the first (plant) crop, the I1 treatment provided ratoons which were up to 15.58% higher than those obtained with the I2 treatment, with cane girths up to 7.69% wider and yields up to 7.29% higher than those observed with the I2 treatment. While the number of nodes per plant did not differ significantly between treatments, there were significant differences in other parameters. Quality parameters (with the exception of extraction percentage) were significantly enhanced by the K3 treatment. The benefit-to-cost ratio (B/C) was higher for the I1 treatment than for the I2, due to a reduced productivity associated with the I2 treatment. At both irrigation levels, the K3 treatment resulted in the highest quality parameters. K1-, K2- and K4-treated plots presented more instances of insect infestations than plots receiving the K3 treatment. Relative to the K3 plots, infestation by the early shoot borer (Chilo infuscatellus) was 18.2, 6.0 and 12.2% higher, respectively, in plots that underwent the K1, K2 and K4 treatments, while infestation by the top borer (Scirpophaga excerptalis) was 21.2, 9.21 and 14.0% higher, and that by the stalk borer (Chilo auricilius) was 10.7, 0 and 8.10% higher. Not all infestation differences between treatments were significant. Our research demonstrates that growing sugarcane in potassium-deficient soils with applications of 80 kg K2O ha−1 under irrigation should be recommended to increase yield and quality while minimising insect infestation and to implement sustainable ratoon sugarcane production.

Farmer evaluation of pesticide seed-coating to control fall armyworm in maize

The arrival of fall armyworm (FAW) in Africa could cause large losses in maize production and affect food security. A new and promising technology to control the pest in the early stages of the maize plant's development is a seed-coating with the insecticide Fortenza Duo, developed by Syngenta and demonstrated in trials and demonstrations during the 2018/19 season in Zambia. Given the urgency of countering the invasion, this study was designed as a rapid and low-cost participatory evaluation of the technology, taking advantage of existing trials and demonstrations while adjusting the standard methodology to fit their lay-out and the timing of the study. The study was organized around an existing trial at the Zambia Agricultural Research Institute, where 44 farmers were invited at mid- and end-seasons, and six on-farm demonstrations organized by Syngenta, where 202 farmers were invited at the end of the regular production season. These evaluations were supplemented with a survey of 153 randomly selected farmers who hosted the demonstrations, and another 162 farmers from the same villages as control. The results showed that farmers scored seed-coated maize plots higher than other non-treated plots during the mid-season evaluation of the trial, but not higher than plots treated with other pesticides. At the end-season, seed-coated maize received slightly higher scores in the overall evaluation but did not score differently for FAW resistance. During the evaluation of on-farm demonstrations, farmers scored the seed-coated maize higher than average for several criteria, in particular for germination/crop stand and resistance to FAW and stalk borer, but the demonstrations did not include a control of untreated maize for comparison purposes. During the survey, however, farmers observed that only 50% of fields with seed-coated maize got infested with FAW vs. 80% in the control. Further, in fields with seed-coated maize FAW infestations occurred about two weeks later than in untreated maize plots. When choosing maize varieties, farmers indicated that yield, grain weight and germination were very important attributes, followed by drought resistance, number of cobs and grain size and, in seventh place, resistance to FAW. When choosing pesticides, farmers listed four criteria as important: convenience, low health risk, low cost, and labor requirements, and listed one criterion, odor, as of minor importance. We concluded that farmers generally evaluated the technology positively. The technology is likely to decrease infestation and damage by FAW, and fit the criteria of farmers in selecting maize seed and pest control methods. However, the results were not conclusive as the demonstrations did not include a proper control.