scholarly journals The influence of two wildfires and biological control agents on the population dynamics of Melaleuca quinquenervia in a seasonally inundated wetland

2021 ◽  
Vol 14 (1) ◽  
pp. 3-8
Author(s):  
Philip W. Tipping ◽  
Melissa R. Martin ◽  
Jeremiah R. Foley ◽  
Ryan M. Pierce ◽  
Lyn A. Gettys

AbstractThe potential of Melaleuca quinquenervia (Cav.) S.T. Blake to reinvade cleared areas was evaluated over a 13-yr period that included two wildfires and the introduction of biological control agents. The first wildfire occurred in 1998 and was followed by a mean of 591.5 recruited seedlings m−2. Recruits from that fire were cleared 7 yr later in July 2005 for a second experiment to evaluate seedling recruitment into cleared areas. Seed rain, seedling recruitment and mortality, and sapling growth rates were measured in four plots located around individual large reproductive trees. A second natural wildfire in 2007 burned through those plots, leading to increases in seed rain followed by a pulse in recruitment of 21.04 seedlings m−2, 96.5% fewer than after the 1998 fire. Recruits in half of the plots around each tree were then treated with regular applications of an insecticide to restrict herbivory by biological control agents, while herbivory was not restricted in the other half. There was no difference in seedling mortality between treatments 1,083 d post-fire (2007) with 96.6% seedling mortality in the unrestricted herbivory treatment and 89.4% mortality in the restricted herbivory treatment. Recruits subjected to the restricted herbivory treatment grew taller than those in the unrestricted herbivory treatment, 101.3 cm versus 37.4 cm. Many of the recruits were attacked by the biological control agents, which slowed their growth. Although solitary M. quinquenervia trees retain some capacity to reinvade areas under specific circumstances, there was a downward trend in their overall invasiveness at this site, with progressively smaller recruitment cohorts due to biological control agents. Land managers should prioritize removing large reproductive trees over treating recently recruited populations, which can be left for many years for the biological control agents to suppress before any additional treatment would be needed.

Plant Disease ◽  
2003 ◽  
Vol 87 (12) ◽  
pp. 1462-1470 ◽  
Author(s):  
S. Rose ◽  
M. Parker ◽  
Z. K. Punja

Potential disease control methods were evaluated against root and stem rot of cucumber (Cucumis sativus) caused by Fusarium oxysporum f. sp. radicis-cucumerinum. Crab/shrimp shell chitin; three composted media; the biological control agents Pseudomonas chlororaphis strain 63-28, Trichoderma harzianum (RootShield Drench), Streptomyces griseoviridis (Mycostop), Gliocladium catenulatum (Prestop WP, Prestop Mix), and Trichoderma (Gliocladium) virens (SoilGard); and the fungicides thiram or benomyl were added at seeding time followed by inoculation with the pathogen. The addition of chitin (4%, vol/vol) to a peat-based medium significantly (P ≤ 0.05) enhanced seedling growth, increased soil pH, and reduced F. oxysporum f. sp. radicis-cucumerinum populations, but the severity of disease was increased. The addition of composted media (greenhouse compost, windrow composted dairy solids, and vermi-composted dairy solids) to the seeding cavity in a rock wool block medium, followed 48 h later by inoculation with F. oxysporum f. sp. radicis-cucumerinum, reduced seedling mortality when measured after 37 days. Greenhouse compost was significantly (P ≤ 0.05) more suppressive than the other two composts, and the suppression was partially eliminated by sterilization of the compost. The biological control agent G. catenulatum (formulated as Prestop WP and Prestop Mix) significantly reduced seedling mortality when it was applied at seeding 24 h prior to inoculation with the pathogen in the rock wool block medium. None of the other biological control agents reduced disease incidence when compared with control plants under these experimental conditions. Pseudomonas chlororaphis and the fungicide thiram both significantly reduced plant mortality at 17 and 24°C when pathogen-infested seed was treated, or when bacteria-treated and fungicide-treated seed were planted into pathogen-infested peat medium at 24°C. Under semicommercial propagation conditions, treatments consisting of Prestop WP, RootShield Drench, My-costop, and windrow composted dairy solids reduced the severity of disease caused by F. oxysporum f. sp. radicis-cucumerinum in two out of three trials. The efficacy of the biological control agents was affected by seasonal differences in growing conditions, which affected the incidence and severity of the disease. The results from this study indicate that several different approaches can be used at seeding to control Fusarium root and stem rot on greenhouse cucumber.


1959 ◽  
Vol 91 (2) ◽  
pp. 116-121 ◽  
Author(s):  
J. Morris Smith

Linaria vulgaris Mill., known commonly as toadflax or butter-and-eggs, is worldwide in its distribution but is a serious weed only in the Canadian provinces of Alberta, Saskatchewan, and Manitoba (Zilke and Coupland, 1954), where it is increasing in importance (Beck, 1954; Carder, 1956; Forbes, 1957). Smith (1956) correlated its relative insignificance as a weed in the other provinces and in the northwestern United States with the occurrence of the curculionid beetle Gylmnaetron antirrhini (Payk.). Investigations on this and other insects that feed on toadflax and an evaluation of their possible use as biological control agents are reported in this paper; also included are some observations on the weedand its natural enemies made since 1950 in all provinces west of Quebec and in the northwestern United States.


1974 ◽  
Vol 25 (5) ◽  
pp. 775 ◽  
Author(s):  
AJ Wapshere

The distribution in Australia of a vegetable fault in wool caused by Noogoora burr, Xanthium stumarium, is outlined. The climates of the region in Australia where the burr produces maximum contamination of wool and where it is of the greatest economic importance are compared with the climates of North America (Texas) and the Indian subcontinent (New Delhi) from where the cerambycids, Mecas saturnina and Nupserha vexator, have been introduced respectively as biological control agents for the weed. The comparisons suggest that neither agent is climatically pre-adapted to the region in Australia where Noogoora burr has the greatest economic importance. On the other hand, a pyralid moth, Oeobia vevbascalis, from Pakistan is well adapted to the climates of the regions affected.


2018 ◽  
Author(s):  
Tina Dancau

Diamondback moth, Plutella xylostella Linnaeus (Lepidoptera: Plutellidae) is a globally distributed pest on brassicaceous crops. This study aimed to follow up with aspects of earlier research, mainly to revisit the potential for overwintering of diamondback moth in the Ottawa area, to investigate present day population dynamics using a life-table approach and to use next generation sequencing to describe the diamondback moth microbiome. A review of the literature has reaffirmed that diamondback moth may not be capable of overwintering in Ottawa with populations likely migrant-driven. The population dynamics and parasitoid community appear to be unaltered after 65 years. The microbiome of diamondback moth larvae was dominated by Enterococcaceae, a family of bacteria hypothesized to aid in resistance and detoxification. This can provide opportunities for the introduction of new biological control agents and tools for diamondback moth management in the future.


2016 ◽  
Vol 159 (2) ◽  
pp. 207-221 ◽  
Author(s):  
Mark A.K. Gillespie ◽  
Geoff M. Gurr ◽  
Steve D. Wratten

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