production occurs ( Anonymous, 2006 ). No economically viable methods of cultural control are currently available. Therefore, effective long-term control of big vein disease is best accomplished through genetic resistance. Within cultivated lettuce, partially
Ryan J. Hayes and Edward J. Ryder
S. Christopher Marble, Andrew K. Koeser, and Gitta Hasing
groundcover species and their ability to outcompete and suppress weed growth in low maintenance landscapes. Other potential future research areas include parasitic weed (i.e., dodder and others), host specificity, and cultural control of weeds in the landscape
Jose G. Franco, Stephen R. King, Joseph G. Masabni, and Astrid Volder
al., 2011 ). Intercropping is a potentially effective cultural control strategy for weeds in organic production systems. Intercropping is the practice of growing two or more crops within the same area such that there is biological and agronomic
Milton E. McGiffen Jr., David W. Cudney, Edmond J. Obguchiekwe, Aziz Baameur, and Robert L. Kallenbach
Yellow and purple nutsedge are problem perennials that resist common control measures. High temperatures, irrigation, and relatively non-competitive crops combine to greatly increase the severity of nutsedge infestations in the Southwest. We compared the growth and susceptibility of purple and yellow nutsedge to chemical and cultural control measures at several locations in southern California. When not controlled, low initial populations of either species led to heavy infestations later in the season. Purple nutsedge was far more prolific in both tuber production and above-ground growth. Summer rotations that included crops with dense canopies severly decreased nutsedge shoot and tuber growth. Cool-season crops planted into heavy nutsedge infestations in the fall are generally unaffected because nutsedge infestations in the fall are generally unaffected because nutsedge soon enters dormancy and ceases growth. Solarization, or pasteurization of the upper soil layers, was effective in decreasing tuber formation. Tillage effectively spread local infestations over larger areas.
Kimberly H. Krahl and William M. Randle
Botrytis diseases are the most common and among the most destructive diseases affecting greenhouse-grown crops. Presently a combination of cultural control and fungicidal sprays are used to control the disease. Increasing energy and labor costs plus evidence of resistance of B. cinerea strains to commonly used fungicides has made the disease more difficult to control. A source of genetic resistance would provide an additional powerful and stable tool to control the incidence of Botrytis disease.
In this study screening techniques for Botrytis resistance in petunia were developed and 40 petunia genotypes were screened for resistance to B. cinerea. A wide range of variability for resistance to B. cinerea was discovered in petunia. Results indicate the presence of useful quantitative-type resistance to B. cinerea in petunia.
Douglas L. Airhart, Kathleen M. Airhart, and John Tristan
Managers of greenhouses used in vocational training or therapeutic programs often face pesticide use restrictions due to medical safety codes, possible sensitivity due to client medications, frequent presence of patient groups, or the added risk of exposure to clients with limited awareness. This review of three horticultural therapy programs emphasizes the practice of preventive measures, manual controls, and limited chemical methods to discourage pest problems and outlines pest control strategies that may not be feasible in commercial greenhouses. The importance and application of integrated pest management and biological pest controls are discussed. Procedures and client activities for sanitation, cultural controls, pest monitoring, and safe application of spray solutions are presented. Client work habits and skills may be developed using the tasks suggested for pest control, and various skill competency levels may be incorporated into the management scheme. The need for client training and task accomplishment may encourage alternative labor-intensive pest-control methods in therapeutic greenhouses.
Dorcas K. Isutsa, Ian A. Merwin, and Bill B. Brodie
Orchard replant disorder (ORD) is a widespread soilborne disease complex that causes stunting and poor establishment of replanted fruit trees. Chemical and cultural control of ORD provide effective, but short-term, control. More-sustainable strategies would involve ORD-resistant rootstocks not yet identified in apple. We tested `Bemali', G11, G13, G30, G65, G189, G210, and G707 clones from the apple rootstock breeding program at Geneva, N.Y., for their response to ORD in a composite soil collected from New York orchards with known replant problems. Clones were tested in the greenhouse in steam-pasteurized (PS), or naturally infested field soils (FS) with about 900 Pratylenchus penetrans and 150 Xiphinema americanum per pot. Plant dry mass, height, root necrosis, and nematode populations were determined after 60 days under optimal growing conditions. Stunting, reduced plant dry mass, and root necrosis were more severe in FS than in PS for most of the clones (P ≤ 5%), but G30 and G210 were substantially more tolerant to replant disorder than smaller ones, but this toleratnce might not be sustained in fields with greater or more prolonged nematode infestations. There is sufficient variation in apple rootstock resistance or tolerance to ORD to suggest that genetic resistance may be identified and developed for better management of orchard replant problems.
Kathryn Homa, William P. Barney, William P. Davis, Daniel Guerrero, Mary J. Berger, Jose L. Lopez, Christian A. Wyenandt, and James E. Simon
Fusarium wilt of basil (FOB), caused by Fusarium oxysporum f. sp. basilici, is an economically damaging disease of field- and greenhouse-grown sweet basil. Growers have observed a resurgence of FOB and susceptibility in FOB-resistant cultivars. Because currently available chemical, biological, and cultural control methods are costly, unsustainable, ineffective, or challenging to implement, new strategies of FOB control are needed. Cold plasma is becoming an increasingly important experimental technology in the food and agricultural industry for pathogen decontamination. To understand the effect of cold plasma treatment on FOB incidence and severity, experiments were conducted by treating FOB mycelium, inoculated sweet basil seedlings, and seeds with various experimental cold plasma treatment devices, all using helium as a feed gas. Initial results indicated that while the cold plasma jet treatment did not result in a significant reduction in mean mycelial growth rate or virulence of the pathogen, direct cold plasma jet treatments on seedlings, as well as a cold plasma dielectric barrier discharge treatment on seeds, did exhibit varying efficacies against FOB. Control of FOB appeared to be strongly dependent on the exposure time to cold plasma. These findings can aid in the standardization of a cold plasma treatment for the commercial basil seed and transplant industry.
L.T. Case, H.M. Mathers, and A.F. Senesac
Container production has increased rapidly in many parts of the U.S. over the past 15 years. Container production has been the fastest growing sector in the nursery industry and the growth is expected to continue. Weed growth in container-grown nursery stock is a particularly serious problem, because the nutrients, air, and water available are limited to the volume of the container. The extent of damage caused by weeds is often underestimated and effective control is essential. Various researchers have found that as little as one weed in a small (1 gal) pot affects the growth of a crop. However, even if weeds did not reduce growth, a container plant with weeds is a less marketable product than a weed-free product. Managing weeds in a container nursery involves eliminating weeds and preventing their spread in the nursery, and this usually requires chemical controls. However, chemical controls should never be the only management tools implemented. Maximizing cultural and mechanical controls through proper sanitation and hand weeding are two important means to prevent the spread and regeneration of troublesome weeds. Cultural controls include mulching, irrigation methods (subirrigation), and mix type. Nursery growers estimate that they spend $500 to $4000/acre of containers for manual removal of weeds, depending on weed species being removed. Economic losses due to weed infestations have been estimated at approximately $7000/acre. Reduction of this expense with improved weed control methodologies and understanding weed control would have a significant impact on the industry. Problems associated with herbicide use in container production include proper calibration, herbicide runoff concerns from plastic or gravel (especially when chemicals fall between containers) and the need for multiple applications. As with other crops, off-site movement of pesticides through herbicide leaching, runoff, spray drift, and non-uniformity of application are concerns facing nursery growers. This article reviews some current weed control methods, problems associated with these methods, and possible strategies that could be useful for container nursery growers.
Raymond A. Cloyd
pathogens; chemical ecology; insecticide resistance; coping with stress; population dynamics; feeding injury; transmission of plant viruses; chemical control; cultural control; host–plant resistance; biological control; monitoring and forecasting; integrated