Weed Science Commons^™

Using Drones For Precision Agriculture, Jiyul Chang, Madhav P. Nepal

Madhav Nepal

In this teaching module, students will learn what Precision Agriculture is and how to apply drone into Precision Agriculture practices. To use data (images) taken by drone, students will learn the basic theory of Remote Sensing. Using images, students learn how to make NDVI (Normalized Difference Vegetation Index) maps and how to apply drone (remote sensing technique) in agriculture.

Competition And Propagule Density Affect Sexual And Clonal Propagation Of A Weed, Daniel Z. Atwater, Wonjae Kim, Daniel R. Tekiela, Jacob N. Barney

Wonjae Kim

Slow Spread Of The Aggressive Invader, Microstegium Vimineum (Japanese Stiltgrass), Emily S.J. Rauschert, David A. Mortensen, Ottar N. Bjørnstad, Andrea N. Nord, Nora Peskin

Emily Rauschert

Microstegium vimineum (Japanese stiltgrass) is a non-native weed whose rapid invasion threatens native diversity and regeneration in forests. Using data from a 4 year experiment tracking new invasions in different habitats, we developed a spatial model of patch growth, using maximum likelihood techniques to estimate dispersal and population growth parameters. The patches expanded surprisingly slowly: in the final year, the majority of new seedlings were still within 1 m of the original patch. The influence of habitat was not as strong as anticipated, although patches created in roadside and wet meadow habitats tended to expand more rapidly and had greater …

Plant Community Associations Of Two Invasive Thistles, Emily S.J. Rauschert, Katriona Shea, Sarah Goslee

Emily Rauschert

In order to combat the growing problems associated with biological invasions, many researchers have focused on identifying which communities are most vulnerable to invasion by exotic species. However, once established, invasive species can significantly change the composition of the communities that they invade. The first step to disentangling the direction of causality is to discern whether a relationship with other vegetation exists at all. Carduus nutans and C. acanthoides are similar invasive thistles, which have caused substantial economic damage worldwide. We assessed the associations between the thistles and the standing flora in four sites in central Pennsylvania in which they …

Japanese Stiltgrass: An Invasive Plant On The Move, Emily S.J. Rauschert, Andrea N. Nord

Emily Rauschert

No abstract provided.

Coexistence Patterns Of Two Invasive Thistle Species, Carduus Nutans And C. Acanthoides, At Three Spatial Scales, Emily S.J. Rauschert, Katriona Shea, Ottar N. Bjørnstad

Emily Rauschert

To better understand the competitive processes involved in invasion by congeners, we examine coexistence patterns of two invasive species, Carduus nutans and C. acanthoides, at three spatial scales. A roadside survey of 5 × 5 km blocks in a previously identified overlap zone provided information about the regional scale. At smaller scales, we surveyed four fields of natural co-occurrence, quantifying the spatial patterns at the field scale by randomly placed 1 × 1 m quadrats and at the smallest scale by detailing plant position within the quadrats. The patterns observed are strikingly different at the different scales. At the regional …

Influence Of Microsite Disturbance On The Establishment Of Two Congeneric Invasive Thistles, Emily S.J. Rauschert, Katriona Shea

Emily Rauschert

The successful establishment of invasive species has been shown to depend on aspects of the invaded community, such as gap characteristics. Biotic resistance may be particularly critical for stopping invaders at early life history stages, but new species can often invade following disturbances, which may create microsites with very different characteristics than are usually present. We examine the response of two invasive thistle species, Carduus nutans L. and C. acanthoides L., to three different microsite characteristics: disturbance type, size, and water availability. The two species initially responded differently to the type of disturbance: C. acanthoides had higher emergence and survival …

Invasional Interference Due To Similar Inter- And Intraspecific Competition Between Invaders May Affect Management, Emily S.J. Rauschert, Katriona Shea

Emily Rauschert

As the number of biological invasions increases, the potential for invader– invader interactions also rises. The effect of multiple invaders can be superadditive (invasional meltdown), additive, or subadditive (invasional interference); which of these situations occurs has critical implications for prioritization of management efforts. Carduus nutans and C. acanthoides, two congeneric invasive weeds, have a striking, segregated distribution in central Pennsylvania, USA. Possible hypotheses for this pattern include invasion history and chance, direct competition, or negative interactions mediated by other species, such as shared pollinators. To explore the role of resource competition in generating this pattern, we conducted three related experiments …

Weed Seed Germplasm Collection 1964-2014 Of The Weed Biology Laboratory, Jack Dekker

Jack Dekker

J. Dekker weed seed germplasm collection; including: Lots 1-3974: 1964-2014; main seed library listed by lot numbers. Lots 649-1457: 1989 all-Iowa Setaria transect study. Lots 1762-1812: 1981; Diane Manthey, North Dakota St. Univ., Setaria collection at Bob Anderson's (USDA, Univ. of Minn) 1960's wild oat study sites. Lots 2389-2595: 1992 north temperate world collection (Japan, Russia, Europe) by J. Dekker. Lots 3270-3685: 1993 Brent Reschly transect study of eastern Iowa conventional and Amish farmers. Lots 3786-3962: 2000 J. Dekker 2000 salt-tolerant Setaria of southern Japan collection. All seed in all these collections belong, and were collected and archived by Jack …

Insect Visitation Of Peduncular And Petiolar Extrafloral Nectar Glands On Castor Bean (Ricinus Communis L.) Plants In Southern California, Victor D. Carmona

Victor D. Carmona-Galindo

Castor bean (Ricinus communis L.) is a myrmecophytic plant species with specialized extrafloral nectar (EFN) glands that serve to attract predatory insects, which in return defend plant-tissues against herbivores. The EFN glands on castor bean plants are located along the leaf petioles as well as on the peduncles of its imperfect (unisexual) flowers. This field-project evaluates the richness, diversity, and species assemblage of insects visiting EFN glands located on (female and male) flower peduncles and leaf petioles on castor bean plants growing in a Southern California coastal landscape. We detected that EFN glands on female-flower peduncles were visited by an …

Continental Diversity Of Chenopodium Album Seedling Recruitment, Jack Dekker

Jack Dekker

Counterpoint perspective to Schutte, et al., (2014) Weed Research 54(16):1-12.: Joint publication with EWRS working group on weed seedling emergence: Andujar, J.G., D.L. Benoit, A. Davis, J. Dekker, F. Graziani, A. Grundy, L. Karlsson, A. Mead, P. Milberg, P. Neve, I.A. Rasmussen, J. Salonen, B. Sera, E. Sousa, F. Tei, K.S. Torresen, J.M. Urbano

Quackgrass: Management On Organic Farms, Heather Westwood, Kara Cox, Eric Gallandt, Eric Sideman, Richard Kersbergen

Eric Gallandt