Noxious Weed Views and Behaviors in Montana after 25 Years of Public Education

In 1994 a general population survey was conducted to evaluate Montanans’ knowledge about noxious weeds, and results from that survey launched an ongoing statewide education campaign. In 2019 we conducted another general population survey to assess the views and behaviors of Montanans as they relate to noxious weeds and to identify new approaches for disseminating noxious weed information. We also asked questions to evaluate changes over the 25-year period, though our ability to make direct comparisons is subject to limitations. We implemented a mail-based survey in March through May 2019. The response rate was 18%, with 830 responses from 4,582 valid mailing addresses. Just under half (48%) of respondents report “little” or “no” knowledge about noxious weeds, which would constitute a 19-point improvement since 1994. A large majority (68%) of respondents indicate that noxious weeds are a “serious” or “very serious” problem, and appreciation for the range of negative impacts associated with noxious weeds is considerable. Most respondents (61%) identify humans as contributing “a lot” to noxious weed spread, and respondents report that their behaviors to prevent the spread of noxious weeds have increased over time. While the 1994 respondents rated television, newspaper, and radio as the best ways to disseminate information about noxious weeds, respondents now also recognize methods such as websites and social media pages as effective. Our survey identifies a need for increased educational messaging for women and people in the 18-39 age group. Overall, our results indicate that individuals who have seen different forms of advertisements and have participated in educational programs are more likely to consider noxious weeds a serious problem and to engage in behaviors to stop their spread.

Allelopathic screening of Malaysian noxious weeds and several medicinal plants as potential alleloherbicides

Aim: This research was conducted to assess the allelopathic potential of 100 plants species, including noxious weeds and medicinal plants of Malaysia as donor plant on the growth of Lactuca sativa (lettuce) as the recipient plant. This study was also carried out to justify common weeds found in Malaysia to act as a natural herbicide for weed management through allelopathy phenomenon. Methodology: Weed and medicinal plant species commonly found in Malaysia were identified according to their morphological characteristics. Sandwich method was carried out to determine the allelopathic potential of weed species through leaf litter leachate mechanism. On the other hand, dish pack method was conducted to discover the allelopathic potential of weed species through volatilization pathway. Results: 100 weed species and medicinal plants commonly found in Malaysia inhibited the radicle and hypocotyl growth of L. sativa by both sandwich method and dish pack method. Among 100 weed species, Passiflora foetida showed the maximum inhibitory effects on L. sativa growth in both sandwich and dish pack method. The highest amount of P. foetida leaf litter (50 mg), completely inhibited the growth of radicle and hypocotyl of L. sativa. Volatilization of weed and medicinal plants leaf litter inhibited the growth of L. sativa with increasing distances of lettuce seed with the weed and medicinal plants leaf litter. Interpretation: The findings of this study provides a base line for identifying plants with allelopathic properties for controlling weed propagation.

Diseases of S. halepense: Possible Role as a Reservoir of Pathogens to Other Plants

Johnsongrass [Sorghum halepense (L.) Pers.] is one of the most noxious weeds distributed around the world. Due to rapid growth, wide dissemination, seeds that can germinate after years in the soil and ability to spread via rhizomes, S. halepense is difficult to control. From a perspective of plant pathology, Johnsongrass is also a potential reservoir of pathogens that can eventually jump to other crops, especially corn (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench]. As one of the most problematic weeds, understanding S. halepense and its diseases can provide useful information concerning its role in diseases of agronomically important crops. An alternative consideration is that S. halepense may provide a source of genes for resistance to pathogens. While some studies have verified that pathogens isolated from S. halepense actually cause disease on host crops through cross inoculation, similarity of disease symptoms and pathogen morphology have been used for identity of the disease agent in most studies. Availability of DNA sequence information has greatly altered and improved pathogen identification, leading to significant changes in phylogenetic assignments. Reclassification of pathogens, especially fungi, raises new questions concerning the role of S. halepense as a disease reservoir. Our goals in this review are to pinpoint, where possible, diseases where S. halepense acts as a significant pathogen reservoir and to point out problem areas where further research is needed.