Management options for large plants of glyphosate-resistant feather fingergrass (Chloris virgata) in Australian fallow conditions

Chloris virgata has become one of the most difficult glyphosate-resistant (GR) grass weeds in summer fallows in the eastern region of Australia. It germinates in several cohorts following rainfall events; therefore, growers are often tempted to wait for most of the weeds to emerge before herbicide application. However, by that time, some seedlings have reached an advanced stage and there is limited information on the efficacy and reliability of alternate herbicides when targeting large plants of GR C. virgata. A series of experiments were conducted to determine the efficacy of alternate herbicides for the control of GR C. virgata. Haloxyfop (80 g a.i. ha-1) on its own, in mixtures, or sequential applications of haloxyfop and paraquat or glufosinate provided 97 to 100% mortality of the 8–10 leaf stage plants. Glufosinate (1500 g a.i. ha-1) also provided complete control of plants at this growth stage. For larger plants at the 24–28 leaf stage, glufosinate, with or without additional tank-mixed adjuvants, generally did not provide full control, however did show very high levels of biomass reduction and panicle suppression at application rates of 750 or 1500 g a.i. ha-1. Haloxyfop (40 to 160 g a.i. ha-1) and clethodim (180 g a.i. ha-1) on their own achieved 96 to 100% mortality at this growth stage. When applied to large plants (40–50 leaf stage), a tank-mix of isoxaflutole plus paraquat demonstrated significantly higher levels of plant mortality and biomass reduction than either herbicide used alone, and this mixture appears to be synergistic when tested via the Colby equation for synergy or antagonism. Plant mortality was greater (83%) when isoxaflutole (75 g a.i. ha-1) plus paraquat (300 g a.i. ha-1) was taken up through the foliage and soil, compared with the foliage alone. This study identified alternative herbicide options for large plants of GR C. virgata.

Potential Bacterial Antagonists for the Control of Charcoal Rot (Macrophomina phaseolina) in Strawberry

The effect of antagonistic bacteria to control Macrophomina phaseolina was evaluated under in vitro, growth chamber, greenhouse and field conditions. A total of 177 bacteria, isolated from Athrocaulon macrostachyum rhizosphere of the Lebrija marsh, were screened for their potential against M. phaseolina (causes charcoal rot in strawberry) by dual culture assay. Of these isolates, 14 most promising strains were molecularly identified by the 16S rDNA sequencing method using the EzBioCloud database. These strains were tested for in vitro hydrolytic enzymes, HCN production, and biocontrol against M. phaseolina in strawberry plants. All the 14 strains produced, at least, one hydrolytic enzymatic activity and one of them, which belongs to Brevibacterium genus (Hvs8), showed the lowest records of disease incidence (20%) and severity (0.4). With these results, greenhouse and field trials were carried out with the Hvs8 strain, compared to non-treated control. In the greenhouse assays, Hvs8 strain increased root dry mass by 30%, over the control. In the field trials, production and fruit quality were not significantly different between Hvs8 treatment and non-treated control, but plant mortality and plant mortality associated to M. phaseolina decreased by more than 24% and 65% respectively, in Hvs8 treatment. This study suggests that Brevibacterium sp. Hvs8 strain could be a candidate for controlling charcoal rot in strawberry.

The effect of using uncertified citrus seeds on huanglongbing disease incidence in Karo District

North Sumatra Province is one of the major citrus producers for Siam cultivars in Indonesia. Recently, it experienced a significant decline in citrus production. One of the causes is the presence of huanglongbing (HLB) disease which results in decreased production and plant mortality. The research aim to obtain information on the origin of citrus seeds and to map HLB incidence in eight subdistricts within Karo District. This research was carried out through direct questionnaires to farmers, visual symptoms scoring, and molecular detection with Polymerase Chain Reaction (PCR). At least two villages were taken from each sub-district and three orchards were taken from each village as samples in January 2019. The results showed that in general, citrus plants aged 3 to 15 years. Mostly, citrus planted in Karo originated from uncertified seedlings bought from local and outside seed breeders in the province of North Sumatra. The highest symptoms severity of HLB diseases based on leaf scores and canopy scores were recorded in Barus Jahe subdistrict with 82-83% intensity. The highest HLB incidence were recorded in three subdistricts namely Kabanjahe, Munte, and Brastagi, each with 100% HLB prevalence. This shows that asymptomatic plants are not always free from CLas pathogens. Certified citrus seeds which are free from systemic diseases, followed by improve farmer’s awareness to apply good agriculture practice the initial to sustain Indonesian citrus agroindustry.

Degraded forest lands and pine plantations in homogeneous ecological areas

Objectives: i) to determine the total degraded areas of EZ in the country, ii) estimate the priority degraded areas for restoration planting, and iii) assess the species and planted areas of the Pinus genus and whether these were within their natural distribution range.Design/methodology/approach: total EZ degradation surfaces and priority degraded areas for restoration plantings were determined with the Germplasm Movement Zones and Restoration Zones of the Comisión Nacional Forestal (NationalForestry Commission, CONAFOR), while planted surfaces were estimated from the CONAFOR records from 2016 to 2018.Results: on degradation, it was shown that three EZ had large areas, six EZ intermediate areas and 32 EZ small areas; two degradation types (III.C and III.D) were prioritized and viable for restoration plantings; four species (23 %) were established outside their natural distribution range while ten (59 %) were within it, three species were undefined.Study limitations/implications: for restoration of areas, it is necessary to avoid high initial plant mortality and poor growth.Findings/conclusions: the north of the country has larger areas with degradation,while the center, north and south have areas with medium and low degradation; planting species outside their distribution range leads to plant adaptation problems.

Fate and adaptive plasticity of heterogeneous resistant population of Echinochloa colona in response to glyphosate

Understanding the fate of heterogenous herbicide resistant weed populations in response to management practices can help towards overcoming the resistance issues. We selected one pair of susceptible (S) and resistant (R) phenotypes (2B21-R vs 2B21-S and 2B37-R vs 2B37-S) separately from two glyphosate resistant heterogeneous populations (2B21 and 2B37) of Echinochloa colona and their fate and adaptive plasticity were evaluated after glyphosate application. Our study revealed the glyphosate concentration required to cause a 50% plant mortality (LD50) was 1187, 200, 3064, and 192 g a. e. ha−1 for the four phenotypes 2B21-R, 2B21-S, 2B37-R, and 2B37-S respectively. Both S phenotypes accumulated more biomass than the R phenotypes at the lower application rates (34 and 67.5 g a. e. ha−1) of glyphosate. However, the R phenotypes generally produced more biomass at rates of glyphosate higher than 100 g a. e. ha−1 throughout the growth period. Plants from the R phenotypes of 2B21 and 2B37 generated 32% and 38% fewer spikesplant−1 than their respective S counterparts in the absence of glyphosate respectively. The spike and seed numbersplant-1 significantly higher in R than S phenotypes at increased rates of glyphosate and these relationships were significant. Our research suggests that glyphosate-resistant E. colona plants will be less fit than susceptible plants (from the same population) in the absence of glyphosate. But in the presence of glyphosate, the R plants may eventually dominate in the field. The use of glyphosate is widespread in field, would favour the selection towards resistant individuals.

Tracking the impacts of El Niño drought and fire in human-modified Amazonian forests

With humanity facing an unprecedented climate crisis, the conservation of tropical forests has never been so important – their vast terrestrial carbon stocks can be turned into emissions by climatic and human disturbances. However, the duration of these effects is poorly understood, and it is unclear whether impacts are amplified in forests with a history of previous human disturbance. Here, we focus on the Amazonian epicenter of the 2015–16 El Niño, a region that encompasses 1.2% of the Brazilian Amazon. We quantify, at high temporal resolution, the impacts of an extreme El Niño (EN) drought and extensive forest fires on plant mortality and carbon loss in undisturbed and human-modified forests. Mortality remained higher than pre-El Niño levels for 36 mo in EN-drought–affected forests and for 30 mo in EN-fire–affected forests. In EN-fire–affected forests, human disturbance significantly increased plant mortality. Our investigation of the ecological and physiological predictors of tree mortality showed that trees with lower wood density, bark thickness and leaf nitrogen content, as well as those that experienced greater fire intensity, were more vulnerable. Across the region, the 2015–16 El Niño led to the death of an estimated 2.5 ± 0.3 billion stems, resulting in emissions of 495 ± 94 Tg CO2. Three years after the El Niño, plant growth and recruitment had offset only 37% of emissions. Our results show that limiting forest disturbance will not only help maintain carbon stocks, but will also maximize the resistance of Amazonian forests if fires do occur.*

Paysandisia archon (South American palm borer).

P. archon is a Neotropical castniid species. It is not considered a pest in most of its native range, probably because it lives mainly on wild palm trees and not on crops; however, Houlbert (1918) and Bourquin (1933) reported that it had the potential to become a serious pest of palms. It was accidentally introduced to Europe from Argentina, as larvae hidden in imported palm trees, mostly Butia yatay and Trithrinax campestris. In Europe, where it is spreading rapidly, P. archon was first found in 2001 in Spain (Aguilar et al., 2001), France (Drescher and Dufay, 2001; Sarto i Monteys and Aguilar, 2001) and Italy (Espinosa et al., 2003; Riolo et al., 2004) and is considered an invasive species in these countries. It is already an invasive pest in France, Italy and Spain, where serious damage and plant mortality has been reported (1000 palm trees have been destroyed) and has become a pest in Buenos Aires, where it was introduced from north-east Argentina (Sarto i Monteys and Aguilar, 2005). The moth is currently listed in the EPPO A2 List (n. 338) of 'Pests recommended for regulation as quarantine pests' (OEPP/EPPO, 2008) and in European Phytosanitary Legislation in AnnexII/Part A/Section II (COMMISSION DIRECTIVE 2009/7/EC of 10 February 2009 amending Annexes I, II, IV and V to Council Directive 2000/29/EC on protective measures against the introduction into the Community of organisms harmful to plants or plant products and against their spread within the Community).

Area wide management of white grub Holotrichia consanguinea Blachard through IPM modules in groundnut

Field experiments were conducted on groundnut for white grub Holotrichia consanguinea Blachard management using different IPM components in Gujarat during kharif 2018 and 2019. Two different eco-friendly modules were evaluated and compare with farmers practices. In Module I included on set of monsoon, spraying of chlorpyrifos 20 EC @ 0.04% on surrounding trees, seed treatment of chlorpyrifos 20 EC @ 20 ml/kg, Placement of aggregation pheromone on host tree (5 block/tree), Soil application of Beauveria bassiana @ 5 kg ha-1 (Min. 2 x 106 CFU/g) + castor cake (250 kg ha-1) before sowing, Application of B. bassiana @ 5 kg ha-1 in plant row with FYM (250 kg ha-1) after 30 days of germination. While Module II used Metarhizium anisopliae instead of B. bassiana. While in farmers practices included application of chlorpyriphos 10 G @ 10 kg ha-1 with urea at initiation of pest attack. Among the evaluated two ecofriendly module and farmers practices the lowest per cent plant mortality (3.03 %) and 0.56 grub/m2 was recorded in Module II. The highest pod and halum yield 2180 and 3942 kg ha-1, yield increase over control 31.00 and 39.37 %, avoidable loss 23.67 and 28.25% was recorded in module II. The maximum (32474 Rs/ha) net realization was found in the treatment of Module II. Looking to the NICBR, the highest (1:5.35) return was obtained with the treatment of Module II followed by Module I (1:2.93)

Responses and screening of white jute (Corchorus capsularis L.) genotypes against salinity stresses

Soil salinity, a serious threat to jute cultivation in saline areas (southern parts) of Bangladesh. Bangladesh Jute Research Institute (BJRI) has developed a moderately salt tolerant White Jute variety (BJRI Deshi pat-8; BJC 2197) in 2013 which can’t grow well in saline areas having more than 8.0 dSm-1 salinity stress. Hence, 23 whitejute accessions and one control variety (BJC 2197) were tested to isolate the salt tolerant accession(s) for hybridization purpose followed by augmented design in farmers’ field having nearly 8.0-9.0 dSm-1 salinity at Patuakhali district during mid-March to mid-August 2019. The experimental plot size was 3.0 m2 (3 m × 1 m) for each genotype having 3 lines of 1.0 m length, plant-plant: 10-15 cm and line- line: 30 cm distance. Soil salinity was recorded during sowing, vegetative and plant maturity stages. In this study, the highest plant height 2.84 m was recorded in Acc. 2750 followed by Acc. 2589 (2.76 m) and Acc. 1779 (2.69 m). The highest fiber yield (9.0 g plant-1) was observed in Acc. 1779 followed by Acc. 2589 (8.40 g plant-1) and Acc. 2750 (8.0 g plant-1). The lowest plant mortality rate (2.5%) was found in Acc.2750 followed by Acc.1779 (6.24%), Acc. 1780 (7.50), Acc. 3556 (11.10%), Acc. 2589 (11.20%) and BJC 2197 (16.5%). Few seeds were germinated in Acc. 3020 and Acc. 3658 but plants were died after 20 days of sowing. Six genotypes of cluster I showed higher diversity in Euclidean cluster analysis. The Acc. 2750, Acc. 1779, Acc. 2589 of cluster I having relative salinity tolerance and good fiber yield capacity would be grown in next year for confirmation as well as hybridization with the existing salinity susceptible variety to develop high yielding white jute variety for saline areas.