Bacterial Wilt of Cucurbits: Resurrecting a Classic Pathosystem

Bacterial wilt threatens cucurbit crop production in the Midwestern and Northeastern United States. The pathogen, Erwinia tracheiphila, is a xylem-limited bacterium that affects most commercially important cucurbit species, including muskmelon, cucumber, and squash. Bacterial wilt is transmitted and overwintered by striped and spotted cucumber beetles. Since there are few commercially available resistant cultivars, disease management usually relies on use of insecticides to suppress vector populations. Although bacterial wilt was initially described more than 100 years ago, our knowledge of disease ecology and epidemiology advanced slowly for most of the 20th century. However, a recent wave of research has begun to fill in missing pieces of the bacterial wilt puzzle. This article—the first review of research toward understanding the cucurbit bacterial wilt pathosystem—recounts early findings and updates our understanding of the disease cycle, including pathogen and vector biology. We also highlight research areas that could lead to more efficient and ecologically based management of bacterial wilt.

Download Full-text

What Do We Need to Know About Disease Ecology to Prevent Lyme Disease in the Northeastern United States?: Table 1.

Journal of Medical Entomology ◽

10.1603/me11138 ◽

2012 ◽

Vol 49 (1) ◽

pp. 11-22 ◽

Cited By ~ 36

Author(s):

Rebecca J. Eisen ◽

Joseph Piesman ◽

Emily Zielinski-Gutierrez ◽

Lars Eisen

Keyword(s):

United States ◽

Lyme Disease ◽

Disease Ecology ◽

Northeastern United States

Download Full-text

First national-scale reconnaissance of neonicotinoid insecticides in streams across the USA

Environmental Chemistry ◽

10.1071/en15061 ◽

2016 ◽

Vol 13 (1) ◽

pp. 12 ◽

Cited By ~ 92

Author(s):

Michelle L. Hladik ◽

Dana W. Kolpin

Keyword(s):

United States ◽

Crop Production ◽

Treatment Plant ◽

The United States ◽

Environmental Data ◽

National Scale ◽

Neonicotinoid Insecticides ◽

Research Areas ◽

The Usa ◽

Stream Transport

Environmental context Neonicotinoids are under increased scrutiny because they have been implicated in pollinator declines and, more recently, as potential aquatic toxicants. Nevertheless, there is currently little information on concentrations of multiple neonicotinoids in surface water. This paper presents a summary of concentrations of six neonicotinoids in streams from across the United States in both urban and agricultural areas. These environmental data are important in determining the potential risk of neonicotinoids to non-target aquatic and terrestrial organisms. Abstract To better understand the fate and transport of neonicotinoid insecticides, water samples were collected from streams across the United States. In a nationwide study, at least one neonicotinoid was detected in 53% of the samples collected, with imidacloprid detected most frequently (37%), followed by clothianidin (24%), thiamethoxam (21%), dinotefuran (13%), acetamiprid (3%) and thiacloprid (0%). Clothianidin and thiamethoxam concentrations were positively related to the percentage of the land use in cultivated crop production and imidacloprid concentrations were positively related to the percentage of urban area within the basin. Additional sampling was also conducted in targeted research areas to complement these national-scale results, including determining: (1) neonicotinoid concentrations during elevated flow conditions in an intensely agricultural region; (2) temporal patterns of neonicotinoids in heavily urbanised basins; (3) neonicotinoid concentrations in agricultural basins in a nationally important ecosystem; and (4) in-stream transport of neonicotinoids near a wastewater treatment plant. Across all study areas, at least one neonicotinoid was detected in 63% of the 48 streams sampled.

Download Full-text

The Status of Weed Science at Universities and Experiment Stations in the Northeastern United States

Weed Technology ◽

10.1614/wt-03-253r1 ◽

2004 ◽

Vol 18 (4) ◽

pp. 1150-1156 ◽

Cited By ~ 6

Author(s):

Jeffrey F. Derr

Keyword(s):

United States ◽

Plant Pathology ◽

Weed Management ◽

Crop Production ◽

Science Research ◽

The United States ◽

Northeastern United States ◽

Weed Ecology ◽

Weed Science ◽

The Status

Weed science is an important component of pest management. Weeds cause approximately 12% loss in United States crop production, reduce crop quality, poison livestock, and adversely affect human health, recreation, and transportation. Herbicides comprise approximately 65% of pesticide expenditures, whereas insecticides and fungicides each comprise less than 20%. The total effect of weeds, including crop losses and costs of control, in the United States was estimated in 1994 to be $20 billion annually. A survey was prepared and mailed to weed scientists at universities and experiment stations in the northeastern United States to determine the number of faculty positions and course offerings devoted to weed science. There are approximately five times as many entomologists and more than three times as many plant pathologists as weed scientists at universities in the northeast. There are more than six times as many graduate students currently in entomology and more than four times as many in plant pathology compared with weed science. Few undergraduate courses in weed science are taught, and most universities have no graduate classes in weed science. There are almost seven times as many undergraduate entomology courses and more than twice as many plant pathology courses as weed science classes in this region. There are more than 17 times as many graduate entomology courses and more than 15 times as many plant pathology courses compared with weed science graduate classes. There are no departments devoted solely to weed science in the northeast, whereas entomology and plant pathology departments are both common. Most universities have little to no faculty assigned to aquatic, forestry, noncrop weed control, weed ecology, or laboratory trials, and numbers assigned to agronomic and horticultural crop weed management are limited. Additional university resources are needed if weed science research, teaching, and extension efforts are to meet the priority needs in weed management.

Download Full-text

Economic Studies Reinforce Efforts to Safeguard Specialty Crops in the United States

Plant Disease ◽

10.1094/pdis-05-20-1061-fe ◽

2021 ◽

Vol 105 (1) ◽

pp. 14-26

Author(s):

M. Fuchs ◽

C. V. Almeyda ◽

M. Al Rwahnih ◽

S. S. Atallah ◽

E. J. Cieniewicz ◽

...

Keyword(s):

United States ◽

Disease Management ◽

Crop Production ◽

The United States ◽

Specialty Crops ◽

Extension Educators ◽

Specialty Crop ◽

Planting Material ◽

Planting Materials ◽

Economic Studies

Pathogen-tested foundation plant stocks are the cornerstone of sustainable specialty crop production. They provide the propagative units that are used to produce clean planting materials, which are essential as the first-line management option of diseases caused by graft-transmissible pathogens such as viruses, viroids, bacteria, and phytoplasmas. In the United States, efforts to produce, maintain, and distribute pathogen-tested propagative material of specialty crops are spearheaded by centers of the National Clean Plant Network (NCPN). Agricultural economists collaborated with plant pathologists, extension educators, specialty crop growers, and regulators to investigate the impacts of select diseases caused by graft-transmissible pathogens and to estimate the return on investments in NCPN centers. Economic studies have proven valuable to the NCPN in (i) incentivizing the use of clean planting material derived from pathogen-tested foundation plant stocks; (ii) documenting benefits of clean plant centers, which can outweigh operating costs by 10:1 to 150:1; (iii) aiding the development of disease management solutions that are not only ecologically driven but also profit maximizing; and (iv) disseminating integrated disease management recommendations that resonate with growers. Together, economic studies have reinforced efforts to safeguard specialty crops in the United States through the production and use of clean planting material.

Download Full-text

Differential Colonization Dynamics of Cucurbit Hosts by Erwinia tracheiphila

Phytopathology ◽

10.1094/phyto-11-15-0289-r ◽

2016 ◽

Vol 106 (7) ◽

pp. 684-692 ◽

Cited By ~ 10

Author(s):

Cláudio M. Vrisman ◽

Loïc Deblais ◽

Gireesh Rajashekara ◽

Sally A. Miller

Keyword(s):

United States ◽

Cucumis Melo ◽

Host Preference ◽

Plant Colonization ◽

Northeastern United States ◽

Erwinia Tracheiphila ◽

Bioluminescent Bacteria ◽

Daily Monitoring ◽

Colonization Dynamics ◽

Preferred Hosts

Bacterial wilt is one of the most destructive diseases of cucurbits in the Midwestern and Northeastern United States. Although the disease has been studied since 1900, host colonization dynamics remain unclear. Cucumis- and Cucurbita-derived strains exhibit host preference for the cucurbit genus from which they were isolated. We constructed a bioluminescent strain of Erwinia tracheiphila (TedCu10-BL#9) and colonization of different cucurbit hosts was monitored. At the second-true-leaf stage, Cucumis melo plants were inoculated with TedCu10-BL#9 via wounded leaves, stems, and roots. Daily monitoring of colonization showed bioluminescent bacteria in the inoculated leaf and petiole beginning 1 day postinoculation (DPI). The bacteria spread to roots via the stem by 2 DPI, reached the plant extremities 4 DPI, and the plant wilted 6 DPI. However, Cucurbita plants inoculated with TedCu10-BL#9 did not wilt, even at 35 DPI. Bioluminescent bacteria were detected 6 DPI in the main stem of squash and pumpkin plants, which harbored approximately 104 and 101 CFU/g, respectively, of TedCu10-BL#9 without symptoms. Although significantly less systemic plant colonization was observed in nonpreferred host Cucurbita plants compared with preferred hosts, the mechanism of tolerance of Cucurbita plants to E. tracheiphila strains from Cucumis remains unknown.

Download Full-text