Influence of Probable Precipitation Futures on Strawberries (Fragaria x ananassa): Results from a Simulated Rainfall Experiment

It is well established that the interacting effects of temperature and precipitation will alter agroecological systems on a global scale. These shifts will influence the fitness of specialty crops, specifically strawberries (Fragaria x ananassa), an important crop in the Northeastern United States. In this study, four precipitation scenarios were developed that are representative of current and probable-future growing season precipitation patterns. Using a precipitation simulator, we tested these scenarios on potted day neutral strawberries. This study generated four primary results: (1) though treatments received different amounts of precipitation, little difference was observed in soil volumetric water content or temperature. However, treatments designed to simulate future conditions were more likely those designed to simulate current conditions to have higher nitrate-in-leachate (N-leachate) concentrations; (2) neither total precipitation nor seasonable distribution were associated with foliar or root disease pressure; (3) while there was a slightly higher chance that photosynthetic potential and capacity would be higher in drier conditions, little difference was observed in the effects on chlorophyll concentration, and no water stress was detected in any treatment; and (4) leaf biomass was likely more affected by total rather than seasonal distribution of precipitation, but interaction between changing rainfall distribution and seasonal totals is likely to be an important driver of root biomass development in the future.

Management of septoria tritici blotch using cultivar mixtures

Septoria tritici blotch (STB) is among the most devastating diseases in European wheat production. In recent years, there has been increased interest in using cultivar mixtures as part of an integrated control strategy against diseases. This study investigated different cultivar mixtures for their ability to control STB across three years and at seven trial sites in Denmark with a range of fungicide strategies, yielding a total of 194 individual cultivar mixture combinations. The mixtures were composed of two, three or four cultivars which were either similar or contrasting in their susceptibility to STB. Across all trials, the cultivar mixtures reduced disease severity significantly, by 14% compared to the component cultivars grown in monoculture. The reductions were larger when the disease pressure was high and when the mixtures included more cultivars. Mixtures composed of four cultivars reduced disease severity significantly, by 24%. Across all trials, cultivar mixtures significantly increased yield by 2% compared to the component cultivars grown in monoculture. The yield increase was significant for plots treated with one or two fungicide applications, and cultivar mixtures increased yield significantly, by 4.4% in untreated plots. The yield increase was smaller for mixtures with a high proportion of resistant cultivars. Based on the results from this study, cultivar mixtures can contribute positively to an IPM strategy, by reducing disease severity for STB and increasing yield. The most pronounced benefits from cultivar mixtures were found in fields with moderate to low fungicide input, under conditions with high disease pressure, when combining four cultivars with varying susceptibilities.

Management of Rice Blast (Magnaporthe Oryzae B. Couch) Using Bioagents and Fungicides Under Hill Rice Ecosystem of Uttarakhand State in India

A field study was conducted during Kharif-2015 and 2016 on management of leaf and neck blast disease of rice caused by Magnaporthe oryzae under hill rice ecosystem. Different treatments including biological control agents like Trichoderma sp. and Pseudomonas sp. and chemical fungicides like tricyclozole, azoxystrobin and carbendazim were used at different growth stages of rice. Among the treatments, tricyclozole @ 0.06% was highly effective followed by azoxystrobin @ 0.1% with application immediately after appearance of disease. Trichoderma and Pseudomonas were not effective in reducing the disease pressure. Bangladesh J. Bot. 50(3): 713-716, 2021 (September)

Effects of mechanical thinning on botrytis bunch rot on Sauvignon blanc wine grapes

Mechanical fruit thinning could be a practical and cost-effective alternative to hand thinning of Sauvignon blanc grapes to increase quality by reducing yield. Botrytis bunch rot, caused by the fungus Botrytis cinerea, is the main seasonal disease risk for grapes grown in New Zealand but it is unknown if this disease is exacerbated by mechanical rather than manual thinning of the vines. It was hypothesised that the damage caused by mechanical thinning would result in more disease or increase disease pressure than hand thinning or no thinning. Botrytis bunch rot was determined in the field at harvest following mechanical thinning in the 2009, 2010 and 2011 seasons compared with an un-thinned control. In the 2011 season, possible mechanisms that may have influenced disease severity were investigated. The parameters investigated were: bunch openness; berry susceptibility to infection; and percentage of bunch debris infected with Botrytis cinerea. Mechanical thinning resulted in the same or lower observed disease severity compared with the un-thinned control in the 2009, 2010 and 2011 seasons while reducing yield as desired. In all seasons, both heavy and light machine thinning treatments reduced incidence of botrytis compared to the un-thinned control and the heavy machine treatment always reduced disease severity compared to the un-thinned control. Berry susceptibility to Botrytis cinerea was a complex interaction between various factors. Heavy machine thinned berries without wounding and inoculation were significantly less susceptible than the un-thinned control. Further investigation will be required to determine if the significant differences observed in berry susceptibility to infection and total infected bunch debris per bunch can be correlated with observed field disease levels.

Response of lentil cultivars to Sclerotinia white mold and Botrytis grey mould infection under irrigated and dryland conditions

Diseases such as Sclerotinia white mold (SWM) caused by the fungus Sclerotinia sclerotiorum (Lib.) de Bary and Botrytis grey mold (BGM) caused by the fungus Botrytis cinerea Pers. may be limiting factors for lentil production in wetter areas of Alberta, Canada. Field trials were conducted at the Lethbridge Research and Development Centre from 2013-2015 to evaluate the response of lentil cultivars to SWM and BGM and yield impacts. Ten lentil cultivars from five market classes were evaluated under irrigated and dry land plots with two planting densities (120 plants m-2 and 160 plants m-2).Year and irrigation had the largest effect on disease incidence, with highest SWM incidence occurring under irrigation in 2013, followed by 2014 and 2015. Conversely, BGM incidence under irrigation was highest in 2015 and lowest in 2013, but levels were lower than SWM. Significantly (P <0.05) lower disease incidences were observed in dryland plots, which also produced higher yield than irrigated plots. Cultivars varied significantly in SWM incidence and yield under irrigated and dryland conditions, perhaps due to variable disease pressure, but there was no consistent trend in cultivar performance. BGM incidence was similar in cultivars, but differed among years. These findings indicate that SWM may be a limiting factor to lentil production in wetter areas, as the ten cultivars from five market classes tested were all highly susceptible to SWM.

Use of the Glomus etunicatum as biocontrol agent of the soybean cyst nematode

This study investigated the effect of arbuscular mycorrhiza (Glomus etunicatum Becker & Gerd.), on the cyst nematode (Heterodera glycines Ichinohe), in a greenhouse. Mycorrhizal and non-mycorrhizal soybean plants were exposed to the pathogen at different initial population densities (0, 500, 1000, 2000, and 4000 nematodes eggs). Soybean growth, nematode reproduction, and the arbuscular mycorrhizal fungus’s capacity to decrease disease pressure were determined after 60 day-olds. The height of the plants was increased by 26% in the presence of arbuscular mycorrhizal fungus (AMF) despite of a higher initial population of cyst nematodes. The root length was, on average, 32.20% was greater in the presence of AMF. The number of nematodes females found in the root system of mycorrhizal plants was 28.21% lower than in non-mycorrhizal roots. These results suggest that AMF G. etunicatum acts indirectly, promoting an improvement in the nutritional plant status creating tolerance to the presence of the pathogen by soybean.

Multienvironment Evaluation of Tannin-Free Photoperiod-Insensitive Sorghum (Sorghum bicolor (L) Moench) for Yield and Resistance to Grain Mold in Senegal

Combining resistance to grain mold with high grain yield in tannin-free white-grained photoperiod-insensitive sorghum is of major interest for farmers in Senegal. In this study, GGE biplot analysis was used to assess the performance, adaptability, and stability of eleven sorghum parental lines and their hybrid combinations for yield and grain mold resistance under Senegalese environments. Eleven inbred lines along with their 22 hybrid combinations and one check were evaluated across three sites during the 2015 and 2016 rainy seasons under natural grain mold infestation. The results of this study showed strong genetic variability among studied genotypes for all measured traits. The highly significant G × E interaction effects for grain yield and panicle grain mold rating score (PGMR) indicated that both traits are influenced by genetics and to some extent by environment. Broad-sense heritability computed was high for all these traits except PGMR, showing a high environmental pressure on this later. The study showed that grain mold pressure in the studied sites decreased following a South-North gradient similar to the rainfall pattern, with the south region wetter, explaining the high disease pressure in Darou and Sinthiou Maleme contrary to Bambey. The GGE biplot analysis performed showed that the first two principal components explained 85.84% of the total variation of GGE sum of squares for grain yield. The which-won-where view of the GGE biplot for grain yield showed that the hybrid HB16 was the most adapted for Bambey area. The ranking of genotypes based on both yield performance and stability showed that HB16, HB5, HB21, HB18, and HB7 were the best hybrids combining high grain yield, high stability performance, and tolerance to grain mold disease across the test environments. These hybrids outperformed the best yielding inbred line P29 (2196.7 kg ha−1) with grain yield advantages ranging 17–60%. Therefore, these hybrids could be recommended to farmers in order to improve sorghum yield in Senegal.

Interspecific interactions between olive trees and grapevines in vineyard agroforestry systems in an arid climate region

In the face of climate change and environmental degradation, conventional viticulture risks the threats of reduced soil fertility, increased heat stress, water scarcity, unseasonal frost, extreme climate events, wind damage, reduced biodiversity, increased erosion, and increased pest and disease pressure. Agroforestry is a sustainable land-use system proven to address many of these conservation and production issues, and yet, agroforestry's applications in viticulture have been severely overlooked. This thesis summarizes the existing body of knowledge surrounding vineyard agroforestry systems in an extensive literature review, and also contributes new research about olive tree and wine grape vineyard agroforestry systems in an arid and irrigated grape growing region in Mendoza, Argentina. The existing body of knowledge surrounding vineyard agroforestry systems shows that the incorporation of trees into vineyards reduces pest and disease pressure, prevents wind damage and erosion, increases stomatal aperture and leaf area, and protects vines against heat and frost damage. Existing research on competition for resources in vineyard agroforestry systems suggests that competition for water may not affect grapevines in a negative way, but that competition for nutrients may affect vines within 4 m of trees, although other studies suggest that trees may actually improve vineyard soil quality. Existing literature also shows that vine yield is reduced within 4 m of trees. Our experiment on a Malbec/olive tree alley cropped vineyard agroforestry system examined the effects of olive trees on grape quality, growth, and production parameters at five different distances from an olive tree hedgerow. Results revealed that proximity of grapevines to the hedgerow was associated with significantly higher quality must, including higher glucose/fructose levels, higher brix levels, higher must density, and higher total acidity. However, within 4 m of the hedgerow, grapevines also experienced significantly lower yield, with yield reductions up to 50 [percent] in vines at 2 m from the hedgerow. Our study also revealed that there were no significant differences in nutrient status between treatments in any pattern that would indicate competition, suggesting that competition for nutrients was not a major competitive factor. The information summarized in this literature review, along with the results of our study, broaden our understanding of vineyard agroforestry systems in different growing contexts and can help determine under which conditions agroforestry should be utilized as an appropriate technology in vineyards. In an arid region with a tree-crop combination of olives and grapevines, the presence of trees was correlated with higher must quality but lower yields. Depending on winemaker goals, the beneficial effects that trees impart on grape must quality parameters, in addition to their whole-farm benefits and ecosystem services, may be determined to outweigh the negative effects that trees have on yield in the rows nearest to trees. Additionally, as many arid grape growing regions anticipate higher temperatures in the coming years due to climate change, utilizing trees in vineyards may be an adaptive strategy for preventing future quality and yield reductions.

Botanical fungicides in the control of soybean leaf diseases / Fungicidas botânicos no controle de doenças foliares na soja

The soybean cultivation (Glycine max (L.) Merrill) is responsible for the highest pesticides use in agriculture in Brazil. There is an environmental and social need to reduce the use of these substances in crops. The alternative products applied in agriculture such as plant extracts and essential oils, becomes necessary and indispensable, mainly in disease control. Among the plants studied, the Noni (Morinda citrifolia L.), has stood out in some studies, where relevant fungitoxic results have been demonstrated, however, there are still few works that prove its viability in the diseases management in field. Thus, this work aimed to evaluate the soybean diseases alternative control through the aqueous extracts and noni essential oil application, in plantings high and low disease pressure. Two field experiments were implemented, with soybean culture, evaluating leaf, fruit aqueous extract and noni essential oil as a fungicidal action. Foliar application of noni extracts and essential oil did not differ from fungicide in Asian Rust and Anthracnose control, in the 2016/17 crop, in both experiments. Soybean productivity was similar in treatments that received leaf extract (1748,8 Kg ha-1), essential oil (1762,5 Kg ha-1) and fungicides (2031,7 Kg ha-1). Where there was no large disease pressure all agronomic characteristics were equivalent, regardless of treatment.