Salisu Sulley

Late water (LW) flooding is a historical cultural practice used in cranberry production for pest suppression and disease management; however, its effects in modern production systems dominated by hybrid cultivars remain poorly understood. This study evaluated treatment-year and subsequent-season responses to LW on fruit rot incidence, yield, fruit quality, and structural and physiological characteristics of cranberry vines in southeastern Massachusetts. Multi-site field trials were conducted across 16 paired LW-treated and conventionally managed commercial beds planted with the hybrid cultivars ’Stevens’ and ’Mullica Queen’. Treatments were implemented during 2021–2023, and responses were assessed during the treatment year and the subsequent growing season. Measurements included fruit rot incidence, yield, total anthocyanin content (TAcy), fruit firmness, berry number, upright ratio, leaf area index (LAI), and total nonstructural carbohydrate (TNSC) dynamics. During the year of LW application, LW was associated with increased fruit rot incidence (P < 0.001), increased TAcy, and decreased fruit firmness in both cultivars, whereas yield was reduced in ’Mullica Queen’ but not in ’Stevens’. LW also reduced berry number and upright ratio, particularly in ’Mullica Queen’. Carbohydrate responses were variable, with no consistent effects on total sugars or starch and cultivar-dependent responses in TNSC. During the subsequent growing season, most treatment effects did not persist; however, yield increased in previously flooded ’Mullica Queen’ beds and was accompanied by higher berry number, whereas no residual yield effect was detected in ’Stevens’. Overall, LW was associated with short-term trade-offs among fruit rot incidence, yield, and fruit quality, followed by limited residual effects and cultivar-dependent responses during the subsequent season. These findings improve understanding of LW responses in modern hybrid cranberry cultivars and may help inform future site-specific management decisions regarding LW implementation

Cranberry fruit rot (CFR) is associated with a complex of more than a dozen fungi—including Coleophoma empetri, Allantophomopsis cytisporea, Botryosphaeria vaccinii, and Colletotrichum spp., which are among the most prevalent CFR fungi across major growing regions—and is a major disease affecting cranberry ( Vaccinium macrocarpon Ait.) production in Massachusetts. Symptoms typically manifest as soft, discolored, and decaying berries right around harvest. This study evaluated the efficacy of Switch (cyprodinil + fludioxonil) and its individual components, Scholar (fludioxonil), and Vangard (cyprodinil) applied alone or in combination with Abound (azoxystrobin) for CFR management. Results showed that Scholar and Switch, particularly when combined with Abound, significantly reduced CFR incidence and improved yield.

Cranberry fruit rot (CFR) poses a major challenge in cranberry production due to the taxonomic diversity of fungi associated with it and increasing restrictions on the most commonly used broad-spectrum fungicides such as chlorothalonils and mancozeb, an ethylene bisdithiocarbamate (EBDC) fungicide. This study evaluated the efficacy of biological fungicides, particularly those containing Pseudomonas chlororaphis (Howler and Esendo) and Bacillus species (Serenade Opti, LifeGard, and Theia), in managing CFR, across seven multi-year field trials conducted in Massachusetts from 2020 to 2023. Biological treatments were tested independently and in combination with chemical fungicides across multiple cranberry cultivars, with evaluations focused on CFR incidence, yield, and fruit quality. Results showed that Esendo, containing P. chlororaphis and azoxystrobin, consistently reduced CFR incidence, achieving efficacy comparable to the grower-standard chemical treatment in specific application regimes. In contrast, solo applications of P. chlororaphis and Bacillus species generally provided limited efficacy, although their integration with chemical fungicides led to varied but often significant reductions in CFR. These findings suggest that biological fungicides can complement chemical treatments in integrated disease management (IDM), reducing chemical use, mitigating resistance risks, and promoting sustainability. The study highlights the potential of biological fungicides in cranberry fruit rot (CFR) management, supporting a shift toward sustainable cranberry production. Further research is needed to optimize application timing, dosage, and product combinations to ensure consistent efficacy in field conditions.

Cranberry fruit rot (CFR), associated with a complex of fungal pathogens including Coleophoma empetri, Allantophomopsis cytisporea, Botryosphaeria vaccinii, and Colletotrichum spp., significantly impacts cranberry ( Vaccinium macrocarpon) production in Massachusetts. Symptoms include softening, discoloration, and decay of berries at harvest. This trial evaluated the efficacy of Cevya (mefentrifluconazole, Fungicide Resistance Action Committee [FRAC] 3) and Omega (fluazinam, FRAC 29), applied alone or in combination with Rampart (phosphonates, FRAC 33), for CFR management. Treatments were compared against a nonsprayed control and a grower standard program composed of QuadrisTop (azoxystrobin + difenoconazole, FRAC 11 + 3) applied at early bloom (EB), Manzate Max (mancozeb, FRAC M03) applied at mid bloom (MB), and Proline (prothioconazole, FRAC 3) applied at late bloom (LB).The study was conducted in 2024 on cranberry cultivar ‘Stevens’ at the University of Massachusetts–Amherst (UMass) Cranberry Station. Several treatments, especially Cevya + Rampart significantly reduced CFR and improved yield on par with the grower standard. These results support the potential of reduced-risk fungicide programs in cranberry production.

Cranberry fruit rot (CFR), associated with a complex of over a dozen fungi including Coleophoma empetri, Allantophomopsis cytisporea, Botryosphaeria vaccinii, and Colletotrichum spp., which are among the most prevalent across major growing regions, is a major disease affecting cranberry ( Vaccinium macrocarpon Ait.) production in Massachusetts. Symptoms typically appear as soft, discolored, and rotten berries at harvest. This study evaluated the efficacy of the novel Syngenta fungicide Switch (cyprodinil + fludioxonil) and its individual components—Scholar (fludioxonil) and Vanguard (cyprodinil)—applied alone or in combination with Abound (azoxystrobin) for CFR management. A field trial was conducted in 2024 at the University of Massachusetts–Amherst Cranberry Station in East Wareham on cranberry cultivar ‘Stevens’, which is widely planted in Massachusetts and is often considered more susceptible to fruit rot than native cultivars (Early Black and Howes). Results showed that several treatments—particularly Scholar applied alone or with Abound and Vanguard and Switch when combined with Abound—significantly reduced CFR incidence and improved yield compared with the nonsprayed control, supporting their potential integration into CFR management programs.

Bacterial spot disease of cucurbits, caused by Xanthomonas cucurbitae , is a major problem in cucurbit‐growing areas worldwide. In the Midwestern region of the United States, pumpkin and squash fields can have greater than 90% infected fruits, leading to high yield losses. While reference genomes are available for this bacterial species, the genetic diversity between different strains and populations is unknown. After performing restriction‐site associated DNA sequencing (RAD‐seq) analysis of X . cucurbitae isolates collected from the Midwestern region, we selected five representative isolates for further characterization, which included whole‐genome sequencing and in vitro enzyme and in planta virulence assays. Our results suggest that minimal genetic diversity exists between these isolates, and that the isolates have differential virulence on different cucurbit host plants. This study contributes to our understanding of X . cucurbitae population dynamics in the Midwestern region and may assist with developing additional management strategies for controlling bacterial spot disease of cucurbits.

Bacterial spot of cucurbits, caused by Xanthomonas cucurbitae , is an emerging disease of cucurbits. This study was conducted to identify Cucurbita species that are resistant to X . cucurbitae . We developed a reliable method for inoculating cucurbit plants by spraying plants with X . cucurbitae suspensions containing carborundum. Symptoms of the disease developed within 7 days after inoculation. Subsequently, we evaluated the virulence of six isolates of X . cucurbitae in the greenhouse and observed that X . cucurbitae isolated from cucurbit fields in Illinois, Michigan, Kansas, Ohio, and Wisconsin were more virulent than the reference ATCC 23378 strain. Then, we screened 81 commercial cultivars of gourds, pumpkins, and squashes, as well as 300 Cucurbita spp. accessions, for their resistance to X . cucurbitae under greenhouse and field conditions. In the greenhouse study, all commercial cultivars and some of the accessions developed typical symptoms of bacterial spot disease, while some of the accessions developed fewer lesions. In the field studies, infection of leaves and fruits was caused by both natural inoculum and spray‐inoculation of plants with a suspension of the X . cucurbitae isolate from Illinois. Among 300 accessions tested, 9 and 21 accessions were classified as resistant and less resistant, respectively. Resistant and less resistant accessions belong to the species Cucurbita maxima , C . maxima subsp. maxima , C . maxima subsp. andreana , and C . okeechobeensis subsp. martinezii . This is the first report of potential resistance to bacterial spot of cucurbits.

This study was conducted to evaluate the effectiveness of crop rotation in managing Xanthomonas cucurbitae, the causal agent of Xanthomonas leaf spot, in pumpkin fields. The study was conducted using ‘Howden’ pumpkin, a susceptible pumpkin cultivar, at four sites with no history of cucurbit production. All sites were planted with pumpkins in the first year of crop rotations. The disease developed at all four sites. In a 3-year rotation with nonhost crops, the severity of Xanthomonas leaf spot in pumpkin plots was significantly (P < 0.05) lower than those of plots in the 2-year rotation with nonhost crops and continuous pumpkin production. Furthermore, X. cucurbitae was recovered from pumpkin plant debris 15 months after harvesting pumpkins in commercial fields, and the pathogen was viable. X. cucurbitae was also isolated from asymptomatic weeds in pumpkin fields. In a greenhouse inoculation of weeds with X. cucurbitae, however, Xanthomonas leaf spot developed only on leaves of burcucumber (Sicyos angulatus) and velvetleaf (Abutilon theophrasti) weeds. In the infested soil with X. cucurbitae, the bacterium was not recovered after 15, 42, and 56 days at 22, 12, and 4°C, respectively. The results showed that crop rotation alone does not provide adequate protection of pumpkin plants against X. cucurbitae.

This study was conducted to evaluate the sensitivity of cucurbit powdery mildew fungus (Podosphaera xanthii) to major fungicides used for managing this pathogen in the Midwestern United States. Fungicides azoxystrobin from the quinone outside inhibitors group, cyflufenamid from the phenylacetamide group, penthiopyrad from the succinate dehydrogenase inhibitors group, quinoxyfen from the quinolines group, and triflumizole from the demethylation inhibitors group were tested for their effectiveness for preventing infection of cucurbits by P. xanthii. In 2015 and 2016, 37 isolates of P. xanthii were evaluated for their sensitivity to azoxystrobin (Quadris 2.08SC), cyflufenamid (Torino 0.85SC), penthiopyrad (Fontelis 1.67SC), and triflumizole (Procure 480SC) on cucumber ‘Bush Crop’ cotyledon leaves. The number of isolates sensitive to tested concentrations of Quadris 2.08SC, Torino 0.85SC, Fontelis 1.67SC, and Procure 480SC was 8 (22%), 21 (57%), 20 (54%), and 23 (62%), respectively. During 2015 to 2018, Quadris 2.08SC, Torino 0.85SC, Fontelis 1.67SC, quinoxyfen (Quintec 250SC), and Procure 480SC were tested for their effectiveness for managing powdery mildew on pumpkin ‘Howden’ in the field. The results showed that powdery mildew was effectively managed in the plots treated with Procure 480SC and Quintec 250SC. However, management of the disease was less successful in the plots treated with Quadris 2.08SC, Torino 0.85SC, and Fontelis 1.67SC.