Early forest stress detection is essential for the preservation of healthy forest ecosystems. The aim of this study is to develop an electronic nose (e-nose) using metal oxide (MOx) gas sensors that can differentiate between stressed and healthy trees by detecting volatile organic compounds (VOCs). An Arduino microcontroller was used to collect data from the gas sensors, while Python was implemented for data processing. The system applied machine learning algorithms such as Linear Discriminant Analysis (LDA), as a supervised learning method, and Principal Component Analysis (PCA), as an unsupervisded learning method, to classify and perform dimensionality reduction on the sensor data. To enhance portability and usability, a printed circuit board (PCB) was designed, creating a compact and efficient e-nose for field testing. The sensor array was tested with various materials found in stressed trees. PCA was also applied to assess sensor sensitivity and evaluate sensor configurations. Initial results demonstrated the e-nose’s ability to distinguish between diseased and healthy trees with significant accuracy. PCA showed good separation of VOC patterns but lower accuracy when detecting multiple target gases. LDA provided clearer distinctions between the two classes with minimal overlap. Although MOx sensors exhibited high sensitivity, their low selectivity for specific gases affected classification accuracy. The high sensitivity of MOx sensors often comes at the expense of selectivity. Future research will focus on identifying specific VOCs emitted by stressed trees using neural networks and improving the e-nose’s ability to detect a wider range of compounds.

In this study, the effect of 13 fungicides on mycelial growth, spore germination and sporulation of Paecilomyces formosus, the main causal agent of dieback disease, were investigated in vitro and in vivo. Treatments included Profiler®, Rovral-TS®, Elit®, Oxychromes®, Cidley Top®, Cuprosit C®, Ortivatop®, Captan®, Acrobat MZ®, Benomyl®, Luna®, Folicur® and Falcon® at different concentrations of 500-3000 ppm. The results showed that the efficiency of different fungicides on fungal development, measured as mycelial growth, spore germination ranged from 36.8 to 100% and 21.7 to 100%, respectively. The inhibition of sporulation was between 0 to 4.3×106 spores mL-1. In vitro, the highest reduction in mycelium growth and spore germination was observed for the fungicides Benomyl®, Luna®, Folicur®, and Falcon® at concentrations of 1000, 500, 1500, 2000 and Ortivatop®, Elite®, Falcon®, Benomyl®, Captan®, and Acrobat MZ® at concentrations of 750, 2500, 2000 1000, 3000, 3000 ppm, respectively. In vivo, the effect of selected fungicides was evaluated on inoculated shoots. The rate of inhibition of pathogen progression using immersion inoculation and the vertical method was 18.7-43.2% and 39.8-45.5%, respectively. The highest inhibition (45.5%) was observed with Luna® fungicide at 500 ppm using the vertical method and the lowest inhibition (18.7%) was related to Benomyl fungicide at 1000 ppm using the immersion method (P≤0.01). No significant advantages were observed in fungicides applications in terms of DBP control compared to those control trees with no-spraying fungicides. In contrast, pruning showed comparative advantages in the management of DBP.

Pistachio dieback (DBP) is a significant disease affecting pistachio trees in Iran, and it has emerged as a serious problem in Kerman province in recent years. This study investigates the role of bacteria as causal agents of DBP under laboratory and field conditions. Samples were collected from infected pistachio orchards in Kerman province from 2015 to 2016. The ability of bacterial isolates to induce disease and colonize vascular tissues was studied using various inoculation methods. Identification of isolates was carried out using biochemical and physiological assays, amplification of the 16S rDNA region, and partial analyses of the gyrA gene. A total of 281 bacterial isolates were obtained from infected trees, of which 148 induced a hypersensitivity reaction on tobacco leaves. Among these, 128 isolates were able to colonize vascular tissues in sub-bark inoculations of pistachio branches under laboratory conditions. In field experiments, 24 selected isolates were able to spread in vascular tissues of pistachio branches and twigs using sub-bark and apical inoculation methods, although disease severity varied. Staphylococcus pasteuri, Bacillus pumilus, Bacillus sp., Acinetobacter radioresistens, Xanthomonas sp., Curtobacterium flaccumfaciens, Pseudarthrobacter oxydans, and Pseudomonas koreensis were identified as being involved in the dieback of pistachio trees. This work demonstrates that a wide range of bacterial genera and species may be involved in DBP, and urgent strategies should be considered for managing the disease.

The bluntleaf dock/ broad-leaved dock (Rumex obtusifolius) is a fast growing, highly competitive and resistant weed. It is endemic to Austria and generally a very common weed in Europe. Rumex obtusifolius prefers nutrient-rich, moist soils. As a light germinator, it spreads easily in patchy plant stands. Its taproot can penetrate compacted, waterlogged and oxygen-poor soil layers to a depth of 2.60 m. It is considered a pest in agriculture, both in field and pasture, because of its rapid growth, ability to vegetatively propagate from leftover roots and its extensive taproot system. The most important management strategy is to prevent dock plants from establishing. If plants are already present in the field, the population must be assessed. If there are up to two dock plants per square meter, single-stock measures such as pricking out or tilling and reseeding are used. If there are more than two plants per square meter, uprooting will help. Furthermore, it will become necessary to adjust the crop rotation. The application of pesticides is possible; however, mechanical removal is preferred. The goal of this study is to develop a CNN (convolutional neural network) that is specially trained to identify dock plants and to capture location and position in the field/pasture. RGB photographs (n = 2500) were collected using an unmanned aerial vehicle and handheld cameras from March to August 2021. The obtained dataset contained photographs showcasing dock plants in all sizes and forms to include different phenotypes and age difference. The network was also trained to differentiate between whole plants and plant parts such as leaves.

Damping-off disease caused by Phytophthora melonis is the most common disease of cucumber seedlings Cucumis sativus L.. To study the efficacy of 8-hydroxy quinoline sulfate (Beltanol®) in control of cucumber damping-off disease, glasshouse experiments were carried out with six treatments at research stations in Tehran, Alborz, and Semnan provinces in Iran. Treatments included 0.3, 0.4, and 0.5 ml∙l-1 of Beltanol as the experimental fungicide, metalaxyl+mancozeb (Rosalaxyl® WP 72%; FRAC code 3 + M03) at 2 g∙l-1 as the standard fungicide along with inoculated and untreated and non-inoculated (healthy) controls. Cucumbers were cultivated from seed in trays, and treatments were applied twice. Once after seed sowing and second time at the 2-leaf stage. Disease incidence was recorded at the 4-leaf stage. Beltanol at 0.3 ml∙l-1 had the least effect among fungicides, with nearly 50% of treated plants showing signs of disease. Application of Beltanol at 0.4 and 0.5 ml∙l-1 decreased disease incidence by 59.55 and 64.47% compared to the inoculated control, respectively. Rosalaxyl® performed better than Beltanol and reduced disease by 83.55%. However, to provide alternatives for proper fungicide rotations, Beltanol at the rate of 0.4 ml∙l-1 may manage damping-off disease in cucumber.

The use of a multi-site fungicide in cucumber downy mildew protection programs are recommended to ensure crops are adequately protected and delay a possible resistance development of high-risk groups of single-site fungicides. Commercially available dicopper chloride trihydroxide (also known as copper oxychloride) based fungicides (M FRAC Group) were assessed for their efficacy against cucumber downy mildew in comparison to a commonly used phosphonate (Fosphite® 53 WSL, P7 FRAC Group) and untreated control. Foliar treatments started with the onset of disease symptoms and were repeated weekly. Disease severity was calculated twice during crop development. Significant differences between the treatments were detected. Fosphite® was the most effective among other treatments, with a reduction in disease severity of 82.6%. Among the copper oxychloride-based fungicides, statistically significant differences were detected. Copertox® and Oksavit® were significantly effective than the other products at the first disease assessment, and Copertox® being the most efficient fungicide at the second disease assessment. Significant differences were also detected among control plots. The efficiency of commercial brands of copper oxychloride in control of cucumber downy mildew was 53-67%. This efficiency is acceptable in normal disease conditions but not desirable in an epidemic situation. If the conditions are favorable for a severe disease epidemic, it is necessary to combine them with more effective fungicides such as Fosphite.

Powdery mildew caused by Podosphaera cerasi is the most important fungal disease of sweet cherries in the Pacific Northwest of the United States. In this study, several factors related to disease epidemiology were evaluated. The experiments were conducted to investigate flower susceptibility to P. cerasi infection by in planta and in vitro inoculation. The susceptibility of fruit at various developmental stages was investigated using defined concentrations of P. cerasi conidia. Furthermore, the threshold of conidial concentration required for fruit infection was determined. The pathogen activity during full bloom was limited and not related to fruit disease incidence and severity at harvest. Foliar infections always preceded fruit infections by an average of 42 days during the 3 years of the study. The onset of fruit infection followed, on average, 66 days after full bloom and appeared simultaneously on all susceptible cherry cultivars in the research orchard. Disease symptoms were only observed on fruit in Biologische Bundesanstalt, Bundessortenamt, and Chemical Industry scale 8 (maturity) in all cultivars examined. During this stage, a concentration of 500 conidia/ml was sufficient to cause fruit infection at harvest. Interaction between the inoculation dates and conidial concentration revealed a dependency of disease development on the host stage at the time of inoculation; the younger the fruit, the more conidia are needed to cause disease at harvest. Molecular studies showed a rapid increase in conidia viability at the transition from asymptomatic to the symptomatic disease of fruit. No evidence of ontogenic resistance of fruit to powdery mildew infection was observed.

ASPERGILLUS FLAVUS:is the main aflatoxin producer in food and feed and has wide ecological niches. Contamination of food products such as pistachio nuts and aflatoxin secretion directly affects food safety and international food product trades. Abilities of 13 yeast strains isolated from 200 soil and pistachio nut samples collected in Iranian orchards to reduce the growth of A. flavus as well as aflatoxin production were assessed in dual culture, volatile and non-volatile compounds tests. The growth of A. flavus was reduced by 32-60%, 13-31% and 40-61% in dual culture, volatile and non-volatile compounds, respectively, while aflatoxin B1 production was diminished by 90.6-98.3%. Based on these assays, five yeast strains were selected for co-inoculation experiments using soil, pistachio hulls and leaf. A significant reduction in colony-forming units (CFU) ranging from 23% to 110% (p < .05) was observed. Molecular, physiological and morphological identification revealed these were strains of Pichia kudriavzevii and Lachansea thermotolerans. Aflatoxin biocontrol with yeast strains possesses many advantages including the ease of commercial production and organic application which is an environmental approach. More investigation is required to understand the efficiency of selective strains to inhibit A. flavus and aflatoxin production as well as withstand predominant abiotic stress in pistachio orchards and mass production in field application.

Mold identification at the species level in environmental samples is a major challenge. Molecular techniques have been widely used for fungal classification, but as most primers are genus-specific, it is laborious to identify unknown samples. In this study, a PCR-based method for the identification of mold at the species level was developed. Therefore, common sequencing primers and combinations of them, targeting specific DNA regions, were tested. Here we present a combination of eight primer pairs to identify mold within a single PCR run. The approach correctly identified mold of unknown species from samples taken at a local bakery, including Penicillium chrysogenum, Penicillium citrinum, Cladosporium sphaerospermum, Paecilomyces formosus, Rhizopus oryzae and Aspergillus niger. Results obtained from the PCR method were successfully validated by chromatographic mycotoxin and microscopy analysis. Findings highlight DNA barcoding as an appropriate tool for mold identification; however, its efficacy is essentially dependent on DNA quality and primer selection.

Powdery mildew of sweet cherry in the Pacific Northwest (PNW) is caused by Podosphaera clandestina, which infects fruit and leaves. Disease symptoms are commonly observed near harvest and such infections are a major concern for offshore cherry markets due to the possibility of diseased cherries providing inoculum to establish the pathogen in a region where P. clandestina has not been reported. The present study was designed to identify periods at which fruit infections are most severe and to determine the efficacy of PNW’s industry postharvest handling practices on the survival of P. clandestina conidia on diseased fruit surfaces. Morphological characteristics and next-generation sequencing (NGS) platform was used to identify the causal agent of foliar and fruit powdery mildew found in the PNW. We combined qPCR and, the use of a viability dye, propidium monoazide (PMA), to differentiate between viable and dead (membrane-compromised) conidia. These tools helped to determine the viability of conidia in real-time. Conidia on the fruit surface naturally lost their viability within a few days of harvest. Postharvest treatments in the PNW include hydrocooling with chlorinated water and methyl bromide fumigation prior to export. These practices were extremely effective in deactivating all conidia on the fruit surface. The residual conidia recovered from the fruit surface after the postharvest treatments failed to establish consistent powdery mildew colonies on the susceptible host leaves; this confirms that diseased, treated cherries are unlikely to serve as a source of inoculum needed to establish the pathogen areas where it has not been documented. After postharvest treatments, regular sampling of conidia up to three weeks after harvest indicated that the conidia were non-viable. Results of this study indicated that the sweet cherry postharvest handling procedures in the PNW are effective for the elimination of the potential sources of P. clandestina inoculum associated with cherry fruit.

The hop powdery mildew fungus Podosphaera macularis persists from season to season in the Pacific Northwestern United States through infection of crown buds because only one of the mating types needed to produce the ascigerous stage is presently found in this region. Bud infection and successful overwintering of the fungus leads to the emergence of heavily infected shoots in early spring (termed flag shoots). Historical data of flag shoot occurrence and incidence in Oregon and Washington State during 2000 to 2017 were analyzed to identify their association with the incidence of powdery mildew, growers’ use of fungicides, autumn and winter temperature, and other production factors. During this period, flag shoots were found on 0.05% of plants evaluated in Oregon and 0.57% in Washington. In Oregon, the incidence of powdery mildew on leaves was most severe and the number of fungicide applications made by growers greatest in yards where flag shoots were found in spring. Similarly, the incidence of plants with powdery mildew in Washington was significantly associated with the number of flag shoots present in early spring, although the number of fungicide applications made was independent of flag shoot occurrence. The occurrence of flag shoots was associated with prior occurrence of flag shoots in a yard, the incidence of foliar powdery mildew in the previous year, grower pruning method, and, in Washington, winter temperature. A census of hop yards in the eastern extent of the Oregon production region during 2014 to 2017 found flag shoots in 27 of 489 yards evaluated. In yards without flag shoots, 338 yards (73.2%) were chemically pruning or not pruned, whereas the remaining 124 (26.8%) were mechanically pruned. Of the 27 yards with flag shoots, 22 were either chemically pruned or not pruned and 4 were mechanically pruned in mid-April, well after the initial emergence of flag shoots. The prevalence of yards with flag shoots also was related to thoroughness of pruning in spring (8.1% of yards with incomplete pruning versus 1.9% of yards with thorough pruning). A Bayesian logistic regression model was fit to the data from the intensively assessed yards in Oregon, with binary risk factors for occurrence of a flag shoot in the previous year, occurrence of foliar mildew in the previous year, and thoroughness of pruning in spring. The model indicated that the median and 95% highest posterior density interval of the probability of flag shoot occurrence was 0.0008 (0.0000 to 0.0053) when a yard had no risk factors but risk increased to 0.0065 (0.0000 to 0.0283) to 0.43 (0.175 to 0.709) when one to all three of the risk factors were present. The entirety of this research indicates that P. macularis appears to persist in a subset of chronically affected hop yards, particularly yards where spring pruning is conducted poorly. Targeted management of the disease in a subset of fields most at risk for producing flag shoots could potentially influence powdery mildew development regionwide.

The hop powdery mildew fungus Podosphaera macularis persists from season to season in the Pacific Northwestern United States through infection of crown buds because only one of the mating types needed to produce the ascigerous stage is presently found in this region. Bud infection and successful overwintering of the fungus leads to the emergence of heavily infected shoots in early spring (termed flag shoots). Historical data of flag shoot occurrence and incidence in Oregon and Washington State during 2000 to 2017 were analyzed to identify their association with the incidence of powdery mildew, growers' use of fungicides, autumn and winter temperature, and other production factors. During this period, flag shoots were found on 0.05% of plants evaluated in Oregon and 0.57% in Washington. In Oregon, the incidence of powdery mildew on leaves was most severe and the number of fungicide applications made by growers greatest in yards where flag shoots were found in spring. Similarly, the incidence of plants with powdery mildew in Washington was significantly associated with the number of flag shoots present in early spring, although the number of fungicide applications made was independent of flag shoot occurrence. The occurrence of flag shoots was associated with prior occurrence of flag shoots in a yard, the incidence of foliar powdery mildew in the previous year, grower pruning method, and, in Washington, winter temperature. A census of hop yards in the eastern extent of the Oregon production region during 2014 to 2017 found flag shoots in 27 of 489 yards evaluated. In yards without flag shoots, 338 yards (73.2%) were chemically pruning or not pruned, whereas the remaining 124 (26.8%) were mechanically pruned. Of the 27 yards with flag shoots, 22 were either chemically pruned or not pruned and 4 were mechanically pruned in mid-April, well after the initial emergence of flag shoots. The prevalence of yards with flag shoots also was related to thoroughness of pruning in spring (8.1% of yards with incomplete pruning versus 1.9% of yards with thorough pruning). A Bayesian logistic regression model was fit to the data from the intensively assessed yards in Oregon, with binary risk factors for occurrence of a flag shoot in the previous year, occurrence of foliar mildew in the previous year, and thoroughness of pruning in spring. The model indicated that the median and 95% highest posterior density interval of the probability of flag shoot occurrence was 0.0008 (0.0000 to 0.0053) when a yard had no risk factors but risk increased to 0.0065 (0.0000 to 0.0283) to 0.43 (0.175 to 0.709) when one to all three of the risk factors were present. The entirety of this research indicates that P. macularis appears to persist in a subset of chronically affected hop yards, particularly yards where spring pruning is conducted poorly. Targeted management of the disease in a subset of fields most at risk for producing flag shoots could potentially influence powdery mildew development regionwide.

In Iran, Phytophthora crown and root rot of pistachio trees (also known as gummosis) destroys a significant number of fertile and non-fertile trees each year. To identify potential biocontrol agents effective in controlling pistachio gummosis, 200 soil samples were collected from 19 pistachio growing regions in Kerman province. Out of the 321 strains tested for antagonistic activity against Phytophthora pistaciae, 13 were selected as potential inhibitors of the disease. The tested strains were able to inhibit Phytophthora growth in dual culture, volatile and non-volatile assays by 14–72%, 12–68% and 27–85%, respectively. The highest inhibition was achieved by three strains identified as Bacillus subtilis using phenotypic characteristics, biochemical and physiological tests as well as sequencing the 16S rRNA genomic region for each strain. Co-inoculation experiments of six months old pistachio seedlings with P. pistaciae and the three selected B. subtilis strains reduced mortality rates by up to 80%. B. subtilis strain BSIPR35 was identified as the most promising biocontrol agent in greenhouse experiments. The ability of the selected strains to withstand drought, high temperature and salinity stresses was further tested. The growth of the strains was reduced under abiotic stresses ranging from 22 to 94%. All strains had the same growth under drought stress, while in salinity and under high temperature strain BSIPR35 acted superiorly compared to the other two strains. The bacterial strains may be effective in inhibiting gummosis in vivo, which requires further investigations.

A large-scale study was conducted to assess which of the five most accessible hermetic storage devices on the Kenyan market fulfill the needs of smallholder farmers by positively impacting three major areas of concern: insect infestation, grain quality, and mycotoxin (aflatoxin and fumonisin) contamination. Efficacy of two hermetic silos (plastic and metal) and three hermetic bags (PICS, GrainPro's GrainSafe™, and Super Grain) was directly compared to current maize storage in polypropylene (PP) bags under local environmental conditions using representative storage volumes during a 6-month storage period. Impact of maize grain stored at typical (∼15%) and recommended (<13.5%) moisture levels and potential efficacy losses through frequent interruption of the underlying hermetic principals was assessed. Hermetic storage significantly reduced the increase in aflatoxin compared to PP bags regardless of the moisture level of the grain. An <5% per month aflatoxin increase was achieved by three of the five devices tested: Metal silo, PICS and GrainSafe™ bag. A strong correlation between grain moisture, storage time and aflatoxin development was found in PP bags, but not in any of the hermetic devices. The same result was not obtained for fumonisin development in stored maize. The rate of Fumonisin increase was similar in all tested devices, including the polypropylene bags, and conditions. The periodic opening of the hermetic devices had no significant effect on the efficacy of the hermetic devices but the repeated disturbance of the PP bags led to a significant increase in aflatoxin levels. The maize weevil Sitophilus spp. was most commonly found with a total incidence of 72%. Grain storage under hermetic conditions reduced insect infestation, grain weight loss and discoloration. However, maize storage above recommended moisture levels led to a distinct odor development in all hermetic devices but not the PP bags. Hence, proper grain drying is a prerequisite for maize storage in airtight conditions.

Podosphaera macularis, the causal agent of hop powdery mildew, is a recurrent threat to hops in the Pacific Northwest because of the potential to reduce cone yield and quality. Early-season pruning is a common practice in hop production for horticultural reasons. Studies were conducted over a 3-year period in a commercial hop yard to quantify the effect of pruning method and timing on disease development, yield, and cone quality factors. A 4-week delay in pruning reduced the incidence of leaves with powdery mildew from 46 to 10% and cones from 9 to 1%, with the specific effect being season dependent. Pruning using chemical desiccants rather than by mechanical means had similar effects on disease levels on leaves. On cones, though, chemical pruning had a small but significant reduction in the incidence of powdery mildew compared with mechanical pruning. Cone yield, levels of bittering-acids, and color were not negatively affected in any individual year or cumulatively over three seasons when pruning treatments were applied repeatedly to the same plots during the study period. Delayed pruning may offer a low-cost means of reducing both the incidence of powdery mildew and early-season fungicide inputs in certain cultivars.

Host resistance, both quantitative and qualitative, is the preferred long-term approach for disease management in many pathosystems, including powdery mildew of hop (Podosphaera macularis). In 2012, an epidemic of powdery mildew occurred in Washington and Idaho on previously resistant cultivars whose resistance was putatively based on the gene designated R6. In 2013, isolates capable of causing severe disease on cultivars with R6-based resistance were confirmed in Oregon and became widespread during 2014. Surveys of commercial hop yards during 2012 to 2014 documented that powdery mildew is now widespread on cultivars possessing R6 resistance in Washington and Oregon, and the incidence of disease is progressively increasing. Pathogenic fitness, race, and mating type of R6-virulent isolates were compared with isolates of P. macularis lacking R6 virulence. All isolates were positive for the mating type idiomorph MAT1-1 and were able to overcome resistance genes Rb, R3, and R5 but not R1 or R2. In addition, R6-virulent isolates were shown to infect differential cultivars reported to possess the R6 gene and also the R4 gene, although R4 has not yet been broadly deployed in the United States. R6-virulent isolates were not detected from the eastern United States during 2012 to 2015. In growth chamber studies, R6-virulent isolates of P. macularis had a significantly longer latent period and produced fewer lesions on plants with R6 as compared with plants lacking R6, indicating a fitness cost to the fungus. R6-virulent isolates also produced fewer conidia when compared with isolates lacking R6 virulence, independent of whether the isolates were grown on a plant with or without R6. Thus, it is possible that the fitness cost of R6 virulence occurs regardless of host genotype. In field studies, powdery mildew was suppressed by at least 50% on plants possessing R6 as compared with those without R6 when coinoculated with R6-virulent and avirulent isolates. R6 virulence in P. macularis appears to be race specific and, at this time, imposes a measurable fitness penalty on the fungus. Resistance genes R1 and R2 appear to remain effective against R6-virulent isolates of P. macularis in the U.S. Pacific Northwest.

Canopy management is an important aspect of control of powdery mildew diseases and may influence the intensity of fungicide applications required to suppress disease. In hop, powdery mildew (caused by Podosphaera macularis) is most damaging to cones when infection occurs during bloom and the juvenile stages of cone development. Experiments were conducted over 3 years to evaluate whether fungicide applications could be ceased after the most susceptible stages of cone development (late July) without unduly affecting crop yield and quality when disease pressure was moderated with varying levels of basal foliage removal. In experimental plots of 'Galena' hop, the incidence of leaves with powdery mildew was similar whether fungicides were ceased in late July or made in late August. Disease levels on leaves were unaffected by the intensity of basal foliage removal, whereas the intensity of basal foliage removal interacted with the duration of fungicide applications to affect disease levels on cones. Similar experiments conducted in large plots of 'Tomahawk' hop in a commercial hop yard similarly found no significant impact on disease levels on leaves from either the duration of fungicide applications or intensity of basal foliage removal. In contrast, on cones, application of fungicides into August had a modest, suppressive effect on powdery mildew. There was also some evidence that the level of powdery mildew on cones associated with fungicide treatment was influenced by the intensity of basal foliage removal. When fungicide applications ceased in late July, there was a progressive decrease in the incidence of cones with powdery mildew with increasing intensity of basal foliage removal. Removing basal foliage two to three times allowed fungicide applications to be terminated in late July rather than late August without diminishing disease control on cones, yield, or cone quality factors. Thus, this study further establishes that fungicide applications made during the early stages of hop cone development have the strongest effect on suppression of powdery mildew on cones. The additive effect of fungicide applications targeted to the periods of greatest cone susceptibility and canopy management to reduce disease favorability may obviate the need for fungicide applications later in the season. This appears to be a viable strategy in mature hop yards of certain cultivars when disease pressure is not excessively high.