Influence of Intraspecific Henbit (Lamium amplexicaule) and Purple Deadnettle (Lamium purpureum) Competition on Soybean Cyst Nematode Reproduction

Abstract

A greenhouse study was conducted to determine the effect of henbit and purple deadnettle density on weed biomass accumulation and soybean cyst nematode (SCN) reproduction. SCN did not impact shoot or root dry weight of purple deadnettle, henbit, or soybean. Foliar and root biomass of henbit and purple deadnettle were comparable but the biomass per stem was higher for purple deadnettle. Shoot and root biomass per pot of henbit and purple deadnettle at corresponding plant densities were statistically similar and were generally higher with increasing plant density. Henbit produced a greater number of stems than purple deadnettle and the least number of stems for both species existed at low densities. Purple deadnettle allowed for more SCN reproduction than did henbit. Weed densities also influenced SCN cyst and egg production but the results were species dependent. The highest SCN reproduction per pot was supported at low to moderate densities of purple deadnettle but at moderate to high densities of henbit. These results suggest that purple deadnettle should be more aggressively managed than henbit in management programs for SCN, but that henbit, especially at high densities, can support SCN reproduction at levels near those of purple deadnettle.

Influence of Winter Annual Weed Management and Crop Rotation on Soybean Cyst Nematode (Heterodera glycines) and Winter Annual Weeds: Years Four and Five

“…They reported no advantages to managing vs. not managing winter annual weeds to reduce SCN population density. This was a surprising result because after 3 yr, henbit and purple deadnettle, the dominant species in our research plots, had been reported in previous greenhouse studies to support SCN reproduction at levels comparable to SCNsusceptible soybean (Creech et al 2007a;Venkatesh et al 2000). Furthermore, the ability of SCN to reproduce on henbit and purple deadnettle under field conditions in Indiana, Illinois, and Ohio had previously been confirmed (Creech et al 2005(Creech et al , 2007b.…”

“…We were surprised by this result and suggested that the relatively low weed density (up to 36 and 75 plants m 22 at West Lafayette, IN, and Vincennes, IN, respectively) in the experimental plot area was not sufficient to support an increase in SCN egg density (Creech et al 2008). In a greenhouse study, we reported that winter annual weed density can influence SCN reproduction and population increase (Creech et al 2007a). By year five, densities of winter annual weed SCN hosts had increased to levels as high as 102 and 245 plants m 22 at West Lafayette, IN, and Vincennes, IN, respectively (Table 3), which are at or above average infestation levels reported in a recent survey of Indiana production fields (Creech and Johnson 2006).…”

“…However, in a survey of Indiana production fields, the density of winter annual weed hosts of SCN was nearly 150 plants m 22 across all fields and, at times, exceeded 400 plants m 22 (Creech and Johnson 2006). In a greenhouse study, the authors reported that winter annual weed density can influence SCN reproduction and population increase (Creech et al 2007a). Our results from the first part of this 5yr study suggest that winter annual weed management to reduce SCN population density may not be warranted in fields with low weed density (Creech et al 2008).…”

A chemical ecological investigation of the allelopathic potential of <i>Lamium amplexicaule</i> and <i>Lamium purpureum</i>

“…Neither oil showed activity against these organisms: C. elegans (LC > 2500 μg/mL), A. salina (LC 50 > 100 μg/ mL), nor Solenopsis (LC 50 > 4000 μg/mL). The absence of nematocidal activity on C. elegans is perhaps not surprising; both L. amplexicaule and L. purpureum are alternative and excellent hosts for the soybean cyst nematode, Heterodera glycines [18,19]. Likewise, insecticidal activity of L. amplexicaule or L. purpureum essential oils should not be expected as these plants are hosts to several generalist phytophagous insects [20].…”

Role of Winter Annual Weeds as Alternative Hosts for Soybean Cyst Nematode

“…First, management of winter annual weeds in low weed density fields failed to influence SCN population density (16). However, research in the greenhouse has indicated that SCN reproduction on winter annual weeds is dependent on weed density (14). Therefore, field research should be conducted in order to determine what density of winter annual weeds can increase SCN populations density.…”