Chapter Two - Crucifer-legume cover crop mixtures for biocontrol: Toward a new multi-service paradigm

Flashcards about Crucifer-legume cover crop mixtures for biocontrol.

What is the purpose of multi-service cover crops (MSCC)?

To provide multiple ecosystem services in the fallow period between two main cash crops, using principles of agroecology.

What benefits can crucifer-legume mixtures provide as compared to sole cover crops?

Improved multi-ecosystem services such as biocontrol and N cycling but trade-offs are uncertain.

What are glucosinolates (GSLs)?

Secondary metabolites in Brassicaceae or crucifer cover crops that release potentially biocidal hydrolysis products like isothiocyanates (ITCs).

What is biofumigation?

Pest, pathogen, and weed suppression by ITCs released from GSLs in cruciferous plants.

Why might crucifer-legume mixtures be beneficial for nutrient cycling?

Legumes can provide nitrogen input through N fixation, improving resource use efficiency.

Name other ecological services, besides weed and pathogen suppression, that MSCCs contribute to.

Plant pollination, maintenance of wild fauna (birds, small mammals, insects, etc.) and contribute to landscape aesthetics

Name one possible disservice of MSCCs.

Pre-emptive competition for water and nutrients with subsequent cash crops.

How do crucifer cover crops suppress pathogens and weeds?

Through allelochemical effects, non-hosting effects, plant cover effects, organic matter addition, and soil structural effects.

Compared to sole crops, how does crucifer density affect mixtures?

A dilution effect occurs as the density of crucifers is halved in bispecific mixtures, making the pest less able to locate and infest its host plants

How do diverse MSCCs, both in root tissue and higher root biomass, help control pests and diseases?

Leads to increased microbial diversity and abundance in the rhizosphere.

How can organic matter, resulting from terminated cover crops, help with soil diseases?

Pathogen suppression by organic inputs has mostly been attributed to indirect effects of higher antagonist diversity and density rather than a decrease in pathogen inoculum

Name two physical soil benefits with the growth of crucifer-legume MSCCs.

Decreasing soil compaction more effectively than pure crops and protecting soil aggregates from erosion and direct rain-drop impact.

What is the role of ITCs in pathogen suppression?

Demonstrated promising biocidal effects on numerous pathogenic microbes including Rhizoctonia solani and Verticillium dahliae

What are some potential disservices of crucifer cover crops related to pathogens?

Hosting pathogens and acting as non-hosts to beneficial organisms such as mycorrhizae.

Do high levels of total GSL always lead to the improved insect suppression?

No. Integrated pest management cannot simply rely on GSL-rich crucifers but must use other methods such as plant mixtures that can generate less favorable conditions for pest reproduction and development.

How may a crucifer-legume MSCC decrease nematode populations versus pure crucifer crops?

Their C:N ratio is generally lower

How does glucosinolate (GSL) production help some crucifer crops?

Can act as feeding deterrents for polyphagous herbivores and feeding stimulant for crucifers specialists

Compared to bare soil, what has traditionally been found with molluscs/slugs under crucifier plants?

They can be found under crucifier plants.

Name some keys to correct biofumigant management?

Important to understand when biocontrol effects occur as it can happen both during the growing period of the cover crop and after cover crop termination.

To economically optimize management of specific cover crop species, what does published literature need to contain?

There is little published literature on the agronomy to economically optimize management of specific cover crop species, and even less for cover crop mixtures.