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- Author or Editor: Jeffrey F. Derr x
Weed management is an important concern for apple producers. Weeds compete with fruit trees for water, nutrients, light and pollination by insects. Weed competition can dramatically reduce apple tree (Malus domestica Borkh.) growth and yield. Weed control practices can impact rodent populations, and insect and disease management in orchards. Use of cultivation can increase soil erosion. Mulches are too expensive for use in orchards and can increase rodent problems. Weeds are generally controlled within the row using herbicides while a grass sod is often used in row middles for erosion control. The most commonly used postemergence herbicides in apples are glyphosate, paraquat, and 2,4-D. Simazine is the most commonly used preemergence herbicide.
Assessing herbicide impacts are difficult due to the indirect effects of weeds on apple (Malus domestica Borkh) growth and development. Herbicide loss will increase potential for development of herbicide-resistant weeds. A limited number of alternatives exist for herbicides currently used in apple production. Switching to certain herbicides increases potential for crop injury. Certain alternatives have higher acute toxicity or are more expensive. No alternatives exist to 2,4-D for broadleaf control in grass alleyways. Nonselective herbicides are alternatives to 2,4-D within the row but pose a greater risk of crop injury. It is difficult to assess long-term impact of 2,4-D loss due to impact on pollination and pest management. Loss of glyphosate will result in yield losses in apple production. Most alternatives to glyphosate are less effective on perennial weed species. Paraquat, one alternative to glyphosate, poses greater hazard to the applicator due to its higher acute toxicity. Diuron is important for rotation with simazine to prevent the development of herbicide-resistance weeds. Norflurazon has an important use in recently planted orchards, where few alternatives exist for yellow nutsedge (Cyperus esculentus L.) control. Oryzalin is commonly used for newly planted orchards and certain alternatives can only be used on nonbearing trees. Alternatives to paraquat pose greater risk of tree injury, although there would be increased worker safety with alternative products. Glyphosate would be the predominate alternative if paraquat was no longer available. Simazine would be the predominate replacement if diuron were no longer available and diuron would be the predominant alternative if simazine was no longer registered for use. Resistance management would be negatively impacted if growers relied on simazine or diuron as their primary preemergence herbicide.
Chemical weed control is an important weed management option in nursery crop production and landscape maintenance. Improved methods of herbicide delivery can increase efficacy of chemical control and minimize off-site movement, applicator exposure, and incorrect herbicide application. Certain innovative technologies show potential for addressing these issues in the nursery industry. Slow-release herbicide tablets have shown promise in container production. Horticultural collars, treated paper, and treated mulch are potential ways of applying herbicides in container crop production and/or landscape maintenance. Horticultural collars contain herbicides between two layers of a carrier such as a landscape fabric. A rapidly degradable paper can be pretreated with an herbicide for a precise application rate. Mulch can be treated with a herbicide prior to use in the landscape for improved weed control. Herbicides applied through the clip-cut pruning system could control weeds selectively in nurseries and landscapes. Each of these methods may address one or more concerns about off-site movement, calibration, and applicator exposure to pesticides.
The tolerance of newly planted apple (Malus domestica Borkh.) and peach [Prunus persica (L.) Batsch] trees to the postemergence herbicide triclopyr was evaluated infield trials. Apple and peach trees were not injured by triclopyr applied at rates ranging from 0.28 to 1.12 kg acid equivalent (a.e.)/ha as a directed spray to soil. No injury was observed following direct application of 10 ml of a triclopyr solution at 2 g a.e./liter to the lower bark of either tree species. Applications of that solution to an individual branch injured or killed the treated apple or peach branch but did not affect the rest of the tree. No reduction in tree growth or injury was noted 1 year after triclopyr application. Applications of 10 ml of a glyphosate solution at 15 g a.i./liter to an apple branch caused severe injury and a growth reduction by 1 year after application, and killed all treated peach trees when applied to one branch. No triclopyr or 2,4-D treatment had affected apple or peach trunk diameter, number of branches, or tree size 1 year after application. Chemical names used: N-(phosphonomethyl)glycine (glyphosate); [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid (triclopyr); (2,4-dichlorophenoxy)acetic acid (2,4-D).
The tolerance of transplanted lanceleaf coreopsis (Coreopsis lanceolata L.), ox-eye daisy (Chrysanthemum leucantheum L.), purple cone flower [Echinacea purpurea (L.) Moench.], and blanket flower (Gaillardia aristata Pursh) to metolachlor was determined in field trials. Metolachlor at 4.5 kg·ha-1 (maximum use rate) and 9.0 kg·ha-1 (twice the maximum use rate) did not reduce stand or flowering of any wildflower species after one or two applications, although plants developed transient visible injury. Combining metolachlor with the broadleaf herbicides simazine or isoxaben resulted in unacceptable injury and stand reduction, especially in ox-eye daisy. Metolachlor plus oxadiazon was less injurious to the wildflowers than metolachlor plus either simazine or isoxaben. Treatments containing metolachlor controlled yellow nutsedge (Cyperus esculentus L.) by at least 89% in both experiments. Treatments containing isoxaben controlled eclipta (Eclipta alba L.). 100% in both studies. Chemical names used: N-[3-(1-ethyl-1-methylpropyl)-5-isoxazolyl]-2,6-dimethoxybenzamide (isoxaben); 2-chloro -N-(2-ethyl-6-methylphenyl) -N-(2-methoxy-1-methylethyl)acetamide (metolachlor); 3-[2,4-di-chloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3 H) -one (oxadiazon); 6-chloro -N,N' -diethyl-1,3,5-triazine-2,4-diamine (simazine).
Tolerance of transplanted black-eyed Susan (Rudbeckia hirta var. pulcherrima Farw.), lanceleaf coreopsis (Coreopsis lanceolata L.), shasta daisy (Chrysanthemum × superbum Bergmans ex. J. Ingram), purple coneflower [Echinacea purpurea (L.) Moench.], and blanket flower (Gaillardia aristata Pursh) to preemergence herbicides was evaluated in container trials. Herbicides were applied at the maximum use rate and twice the maximum use rate. Dithiopyr, pendimethalin, and prodiamine provided excellent control of spotted. spurge (Euphorbia maculata L.) and yellow woodsorrel (Oxalis stricta L.) with little injury to the five herbaceous perennials. DCPA, oxadiazon, and metolachlor were tolerated by all treated species, but these chemicals provided lower control of one or both weed species. Oryzalin, isoxaben + trifluralin, and napropamide caused unacceptable injury and shoot fresh-weight reductions in some of the perennials at one or both application rates. Chemical names used: dimethyl 2,3,5,6-tetrachloro-1,4-benzenedicarboxylate (DCPA); S,S-dimethyl 2-(difluoromethyl) -4-(2 -methylpropyl)-6-trifluoromethyl-3,5-pyridinedicarbothioate(dithiopyr);N-[3-(1-ethyl-1-methylpropyl)-5-isoxazolyl]-2,6-dimethoxybenzamide(isoxaben); 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide(metolachlor);N,N-diethyl-2-(l-naphtha1enenyloxy) propanamide(napropamide);4-(dipropylamino)-3,5-dinitrobenzenesulfonamide (oryzalin);3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethy1)-l,3,4-oxadiazol-2-(3H)-one (oxadiazon); N-(1-ethylpropyl) -3,4-dimethyl-2,6-dinitrobenzamine (pendimethalin); N,N-di-n-propyl-2,4-dinitro-6-(trifluoromethyl)-m-phenylenediamine (prodiamine); 2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzamine (trifluralin).
Disks of several geotextiles, paper, fiberglass, and black polyethylene were compared with the herbicides oxyfluorfen plus pendimethalin, oxadiazon, and oryzalin plus benefin for suppression of weed growth around container-grown Southwestern white pine (Pinus strobiformis Engelm.), Chinese pistache (Pistacia chinensis Bunge.), and `Fashion' azalea [Rhododendron indicum (L.) Sweet × `Fashion']. The greatest weed control was obtained with a combination geotextile-preemergence herbicide (trifluralin) disk, indicating a possible new method of container weed control. Several of the barrier materials, including heavy wrapping and compressed peatmoss papers, black polyethylene, and one spunbonded geotextile, were inferior due to degradation or to weeds growing around the disk edges or center hole. No difference in crop growth was noted among the treatments. Chemical names used: 2-chloro-1- (3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl) benzene (oxyfluorfen); N-(1-ethylpropyl)-3,4 -dimethyl-2,6-dinitrobenzenamine (pendimethalin); 3-[2,4-dichloro-5 -(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon); 4-(dipropylamino) -3,5 -dinitrobenzenesulfonamide (oryzalin); N-butyl-N-ethyl-2,6 -dinitro-4-(trifluoromethyl) benzenamine (benefin); 2,6-dinitro-N,N-dipropyl-4-(ttifluoromethyl)benzenamine (trifluralin).
Tall fescue (Festuca arundinacea) and hybrid bluegrass (Poa pratensis L. × Poa arachnifera) can both be successfully grown in the transition zone of the United States. However, each grass has limitations. Tall fescue is susceptible to the fungal pathogen Rhizoctonia solani, whereas slow establishment and susceptibility to weed infestations limit hybrid bluegrass. Previous studies have shown the benefits of combining kentucky bluegrass with tall fescue in seeding mixtures. Research was conducted to evaluate the impact of two seeding combinations of hybrid bluegrass and tall fescue (one combination seeded at a 1.9:1 seed count ratio favoring tall fescue, the other combination seeded at a 1:1.8 seed count ratio favoring hybrid bluegrass) as well as monocultures of the species on turfgrass cover, weed species infestation, brown patch disease severity caused by R. solani, sod strength and species ecology. The seeding combinations had lower weed density during establishment and greater turf cover than the monoculture of hybrid bluegrass. The monoculture of tall fescue was subjected to more brown patch disease than the seeding combinations during and after the first year of establishment. Brown patch infestations likely reduced tall fescue cover and led to a species shift favoring hybrid bluegrass in the seeding combinations based on tiller count and weight data. Seeding combinations of tall fescue and hybrid bluegrass are beneficial from an epidemiological perspective because they reduce disease and weed infestations compared with monocultures of either species. From an agronomic perspective, the seeding combination favoring tall fescue provided the densest turf, whereas the seeding combination favoring hybrid had the greatest sod strength. Chemical name used: clopyralid (3,6 dichloropyridine-2 carboxylic acid)
Mobile device applications (apps) have the potential to become a mainstream delivery method, providing services, information, and tools to extension clientele. Testing, promoting, and launching an app are key components supporting the successful development of this new technology. This article summarizes the considerations and steps that must be taken to successfully test, promote, and launch an app and is based on the authors’ experience developing two horticulture apps, IPMPro and IPMLite. These apps provide information for major pests and plant care tasks and prompt users to take action on time-sensitive tasks with push notifications scheduled specifically for their location. App testing and evaluation is a continual process. Effective tactics for app testing and evaluation include garnering focus group input throughout app development and postlaunch, in-house testing with simulators, beta testing and the advantages of services that enhance information gained during beta testing, and postlaunch evaluations. Differences in promotional and bulk purchasing options available among the two main device platforms, Android and iOS, are explored as are general preparations for marketing the launch of a new app. Finally, navigating the app submission process is discussed. Creating an app is an involved process, but one that can be rewarding and lead to a unique portal for extension clientele to access information, assistance, and tools.
With increased mobile device usage, mobile applications (apps) are emerging as an extension medium, well suited to “place-less” knowledge transfer. Conceptualizing, designing, and developing an app can be a daunting process. This article summarizes the considerations and steps that must be taken to successfully develop an app and is based on the authors’ experience developing two horticulture apps, IPMPro and IPMLite. These apps provide information for major pests and plant care tasks and prompt users to take action on time-sensitive tasks with push notifications scheduled specifically for their location. Topics such as selecting between a web app and a native app, choosing the platform(s) for native apps, and designing the user interface are covered. Whether to charge to download the app or have free access, and navigating the intra- and interinstitutional agreements and programming contract are also discussed. Lastly, the nonprogramming costs such as creating, editing, and uploading content, as well as ongoing app management and updates are discussed.