question: what is horticulture?

Defined by the American Society for Horticultural Science as, “the art and science of producing, improving, marking, and using fruits, vegetables, flowers, and ornamental plants,” horticulture is an important component of society that positively impacts citizen’s quality of life. Such improvements can take the form of, for example, increased nutrition, more attractive living environments, or a demonstration of cultural identity.

From an economic perspective, horticulture is a $17 billion [USD] industry that produces more than 2.4 billion tons of goods annually as well as provides employment and income to various participants of horticultural supply and value chains. It is also a growth market with enterprises that vary vastly in size.

the horticulture supply chain
Source: International Society for Horticultural Science, exerted from ‘Harvesting the Sun’, 2012

Each supply and value chain has a number of different stakeholders who are affected by the flow of goods. The actions taken by each link of the chain influences the other members. Therefore, cooperation plays a strong role in the effectiveness of a supply or value chain.

supply chain history
Source: International Society for Horticultural Science, exerted from ‘Harvesting the Sun’, 2012

With such a wide-range of stakeholders, the types of employment provided by horticulture are many. The end-products of these services provide aesthetic, sociological, and psychological benefits. Such benefits range from being able to enjoy fresh fruit on a daily basis to drinking a fine bottle of wine with friends to being able to send a sick family member flowers to sitting in a well-tended park on Sunday afternoon. Horticulture is able to provide these benefits because it differs from other plant sciences and botany as it it incorporates both art and science.

employment sectors in horticulture
Source: International Society for Horticultural Science, exerted from ‘Harvesting the Sun’, 2012

In response to massive consumer demand for horticultural products and a quickly growing population, it has been argued that large-scale production, which is generally vertically integrated, is the only production system capable of consistently meeting global demand. This capability is grounded in the shift from the use of manual labor towards the expansion of the use of machinery and robotics. It has also been asserted that large-scale production is more efficient. However, evidence contrary to the aforementioned assertions has been produced, indicating that small-scale production is as productive as large-scale production. However, due to widespread modernization in the horticultural field, it is often much more difficult for small-scale producers to compete in the market which in turn allows for a concentration of economic power.

Nonetheless, changes in consumer demand may work in favor of small-scale producers as consumers seek out more authentic food experiences, diversity, and are more interested in supporting their local communities. If small-scale producers can effectively exploit such demands as well as provide high-quality products at reasonable prices, they are likely to be able to capture a greater market share. Specific opportunities can be found in tropical fruit production and the diversification of vegetables – two areas where both demand and consumption has steadily increased.

Current issues being faced by the horticultural industry, regardless of size, include controversy associated with seed production, changing weather patterns and climate, soil and fertilizer management, disease and pest control, rising energy costs, and water scarcity.

sources:

https://articles.extension.org/pages/64847/what-is-horticulture
http://www.ashs.org/?page=horticulture
http://www.harvestingthesun.org/sites/default/files/ISHS-Harvesting-the-Sun-full-profile.pdf

an introduction to community supported agriculture (csa)

First introduced in Japan and Switzerland in the 1970s, community supported agriculture (CSA) is a form of partnership between farmer and consumer.  They enter into a contract which provides consumers with a certain number of ‘shares’ in the farm. Each share provides the consumer a box (or bag or bucket or …) of vegetables or other products at a regular interval. 

There are four basic components of a CSA:

  1. Partnership: a mutual agreement between the producer and the consumer is established for the growing season
  2. Local Production: the exchange is local, i.e. a part of the community, in order to facilitate the relocalizing of the human-food relationship
  3. Solidarity: a unifying relationship is developed that is beneficial to both producer and consumer
  4. A Producer/Consumer Tandem: the direct person-to-person relationship, i.e. no intermediaries or hierarchies, is established

The establishment and execution of a CSA have several benefits and challenges for producers and consumers that are summarized below.

Challenges

Opportunities

Producers

  • Potential for a bad worth of mouth
  • Increased management requirements
  • Time demands → customer relations
  • Packaging and distribution costs

Consumers

  • May feel like they are not getting their money’s worth
  • Lack of choice
  • May be expensive
  • ‘Long-term’ commitment
  • Short shelf life (no preservatives)
  • A significant amount of produce that requires cooking
Producers

  • Marketing before the growing season
  • Consistent cash flow
  • Development of customer relationships → loyalty
  • Shared risk
  • Cuts out the ‘middleman’
  • Little capital investment
  • Word of mouth advertising

Consumers

  • Access to super fresh produce
  • Development of relationship with producer
  • Contact with the farm

Society

  • Reduced environmental impact of food(?)

For the implementation of a successful CSA, the participants – both farmers and consumers – must have the ‘right’ type of personality, i.e. committed and patient. However, if such a relationship can be established, CSAs are a very viable marketing strategies that can be used by small farmers to remain competitive in an environment largely dominated by industrialized agriculture.

sources:

http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex3482?opendocument
http://edis.ifas.ufl.edu/fy597

question: what is the difference between plant resistance and plant tolerance?

Plant tolerance is the characteristic of a plant that allows a plant to avoid, tolerate or recover from attacks from insects, among other things, under conditions that would typically cause a greater amount of injury to other plants of the same species. These inheritable characteristics are what influence the ultimate degree of damage caused by a pest. Tolerance in terms of agricultural production means that despite stress from a pest or disease, the production levels will remain above the economic threshold.

Resistance means that a plant completely immunizes itself from a particular stress.  This is typically a biotrophic pathogen infection. The host has a resistance gene which prevents the proliferation of the pathogen. The pathogen typically contains an avirulence gene which triggers plant immunity.

Resistance and tolerance are the best defense mechanisms of plants against pests. 

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developing new plants that are resistant to freezing  photo credit: phys.org

There are two main types of resistance: ecological resistance/pseudo-resistance and genetic resistance. Ecological resistance is resistance related to favorable environmental conditions at a given location at a particular time. This type of resistance can be broken down into 3 forms:

  1. Host evasion – this phenomenon occurs when a host passes through the susceptible stages very quickly or during a period when pests are fewer.  This type of resistance applies to an entire species population.
  2. Induced resistance – this type of resistance is the result of some type of changed condition for the plant, such as an increase in available nutrients or water
  3. Escape – this is more or less luck as there is an absence of infestation or injury to a host plant as a result of incomplete infestation.

Genetic resistance is resistance related to (you guessed it) plant genetics.  There are several types of genetic resistance:

Resistance based on the number of genes

  • Monogenic – controlled by a single gene which makes it easy to both incorporate and exclude in plant breeding programs
  • Oligogenic – controlled by a few genes
  • Polygenic – controlled by several genes
  • Major Gene Resistance – controlled by one or a few major genes (vertical resistance) 
  • Minor Gene Resistance – controlled by many minor genes; the cumulative effect of minor genes is called adult/mature/field/horizontal resistance

Resistance based on biotype reaction

  • Vertical Resistance – specific resistance against specific biotypes
  • Horizontal Resistance – effective against all known biotypes; nonspecific resistance

Resistance based on miscellaneous factors

  • Cross-Resistance – when resistance against a primary pest results in resistance to a secondary pest
  • Multiple-Resistance – different environmental stresses (e.g. insects, diseases, nematodes, heat, drought, etc.) results in a new resistance

Resistance based on evolution

  • Sympatric Resistance – resistance that is acquired through the coevolution of a plant and insect (which is why it is important to protect our native pollinators!); governed by major genes
  • Allopatric Resistance – not governed by a co-evolution; governed by many genes

There are three mechanisms of resistance in plants.

Antixenosis (non-preference) resistance mechanisms are those by which host plant has characteristics that result in non-preference for insects in terms of shelter, oviposition, feeding, etc. There are morphological or chemical factors that influence insect behavior and results in the poor establishment of insects. Plant shape and color can also be an important influencing factor.

Antibiosis is the negative effect of a host plant on the biology of an insect. This can include decreased rates of survival, development and/or reproduction and is a result of biochemical and biophysical factors. Antibiosis may be a result of the presence of toxic substances, the absence of essential nutrients or a nutrient imbalance. Physical factors, such as thick cuticles, glandular hairs and silica deposits, also contribute to antibiosis.

Tolerance is a plant’s ability to grow and produce an acceptable yield despite a pest attack. Tolerance is typically attributed to plant vigor, regrowth of damaged tissue and a plant’s ability to produce additional stems/branches.

Both plant tolerance and plant resistance are extremely important to IPM efforts as it helps to reduce costs and amount of other control tactics that need to be implemented. This includes improving the efficacy of insecticides and promoting non-chemical benefits like shifts in predator-prey relationships and reduced pest populations.

The benefits of the use of resistant cultivars are numerous as this method has a high level of specificity, is eco-friendly, lower cost and adaptable to a given situation. The benefits are limited only by the amount of time required to develop new cultivars in breeding programs and by a lack of known resistance genes that can be used. To identify and capture relevant genes, crop wild relatives are often used.

biological control via entomophatogenic viruses: baculovirus

Entomopathogenic viruses are those that infect and kill insects.  They are superior to regular pesticides in that they are not harmful to humans or other vertebrates. Furthermore, each viral strain attacks only a limited number of insect species which helps to mitigate unpredicted damage.

baculo
Photo Credit: aibn.uq.edu.au

There are two types of entomopathogenic viruses:

  1. Baculoviridae (ds DNA)
    1. Nucleopolyhedrovirus
    2. Granulovirus
  2. Reoviridae (ds RNA)
    1. Cypovirus

However, the Baculoviridae viruses are the ones that are most commonly used.  They are found only in invertebrates and despite rigorous testing have not been shown to negatively affect vertebrates and plants.  They also have a narrow host insect range which is typically restricted to the original host genus.  

The mode of action for Baculoviridae is as followed:

Baculovirus is sprayed onto foliage –>  Caterpillar consumes the virus  –> The protein encapsulating the Baculovirus DNA dissolves and the DNA enters the stomach cells –> Baculovirus DNA is replicated by the stomach cells until the stomach cells rupture –> The caterpillar stops eating  –> Baculovirus is spread throughout the caterpillar causing a general systemic infection    –> The caterpillar dies within days

Leo turk 3 leo
Photo Credit: Leo Graves, Oxford Brookes University via oetltd.wordpress.com

 

The biggest issue related to the use of this method is the amount of time required before the pest dies.  This is noted as being the number one reason why this method is not used on a more wide scale basis.

Baculoviruses are created in vivo and production is often automated which makes it predictable and inexpensive because of the use of inexpensive growing mediums and the natural process of fermentation.  It is estimated that application in the USA costs $6-10/acre which is competitive with prices for industrialized chemical pest control options.

In order for the use of Baculovirus to expand the following improvements must be made:

  1. Genetic engineering must result in a 50% increase in the speed of the kill time
  2. Residual activity of the virus must be increased from 2 – 4 days to >7
  3. The role of Baculoviruses must be strengthened within successful IPM programs
  4. More cost-effective cell culture for the mass production of wild type and genetically modified Baculoviruses must be developed

A major example of success using a Baculovirus is the control of the Gypsy Moth (Lymantria dispar) using the entomopathogenic virus LdMNPV.

sources:

https://www.researchgate.net/publication/233795389_Genomics_of_Entomopathogenic_Viruses_Insect_Pathogens_Molecular_Approaches_and_Techniques

http://www.fao.org/docs/eims/upload/agrotech/2003/active_agents.pdf

https://www.researchgate.net/publication/263765284_Entomopathogenic_Viruses

http://web.entomology.cornell.edu/shelton/cornell-biocontrol-conf/talks/georgis.html

http://www.biopestlab.ucdavis.edu/files/131018.pdf

an introduction to integrated pest management (IPM)

Integrated pest management (IPM) is a long-term pest prevention program that focuses on ecosystem-based strategies for the control of pest related issues. This is accomplished through a combination of techniques including biological control, habitat manipulation, modification of cultural practices and the use of resistant cultivars. The use of chemical pesticides is then restricted to applications only after strict monitoring that is based on established guidelines indicates that stronger measures are required for pest management. In the event that chemical agents are required, they are applied in a targeted manner intended to minimize risks to the environment, other organisms (especially beneficial and non-target organisms) and to human health.

The 8 principles of IPM are as followed:

  1. In an effort to prevent and/or combat pests, the following intelligent production practices shall be used: crop rotation, sustainable cultivation techniques, resistant/tolerant cultivars and certified seed production systems, balanced fertilization, irrigation and drainage techniques, proper hygiene measures and the protection and proliferation of beneficial organism.
  2. The use of biological, physical and non-chemical control methods must be preferred to chemical options as long as the non-chemical options provide acceptable pest control.
  3. In the event that pesticides must be applied, they shall be target-specific and strategically applied in an effort to reduce negative health outcomes.
  4. Pesticides shall be used only on an as-needed basis and the frequency and intensity of use  should be minimized in order to reduce the risk of resistance populations.
  5. In cases where pest resistance has been established and repeat pesticide application is necessary, anti-resistance strategies should be integrated into control efforts.  
  6. Record keeping is essential and should be based on detailed records in order to determine the efficacy of pest control programs – especially in the case of chemical inputs.
  7. Monitoring efforts are essential in order to track pest presence.  This can be accomplished via observations, forecasting and early diagnosis systems and information, as well as information from professionally qualified .  
  8. The information garnered by monitoring efforts shall be used to determine when and which plant protection measures will be taken.  There should be scientifically supported threshold values upon which to base decision making.  Said values should be adapted to local conditions including climate, crop type and topographical qualities.

sources:

https://www.nap-pflanzenschutz.de/en/practice/integrated-plant-protection/general-principles-integrated-plant-protection/
http://www.ipm.ucdavis.edu/GENERAL/ipmdefinition.html
http://www.fao.org/agriculture/crops/thematic-sitemap/theme/spi/scpi-home/managing-ecosystems/integrated-pest-management/ipm-how/en/

 

 

question: what is the difference between intensive and extensive agricultural systems as they relate to livestock production?

Intensive livestock production systems are those that use higher amounts of labor and capital relative to the land area.  The best-known examples are Concentrated Animal Feeding Operations (CAFOs) which house large numbers of animals in small spaces.  These operations are dependent on food that was likely produced thousands of kilometers/miles away which increases demand for fossil fuels.  They also create large amounts of concentrated waste, CO2 and methane which is damaging to the environment and cannot be reintegrated into the ecological system of a farm because of the monoculture nature of these types of production systems.

intensieve-veehouderij1
Photo Credit: thinkability.com

In contrast, extensive farming systems are dependent on the carrying capacity (soil fertility, terrain, water availability, etc.) of a given piece of land and often responds to the natural climate patterns of an area.  It does not depend on a large amount of pesticides, fertilizers or other chemical inputs relative to the land area being farmed.  This is how most livestock production takes place int he world.  Herders are the classic example.

mongolian-grasslands
Photo Credit: oregonstate.edu

The main difference between the two types of agriculture is that extensive agriculture requires much more land for production and profitability than intensive production.  As such, extensive agriculture is often practiced where population densities are low and land is inexpensive.

The danger of intensive agriculture, apart from environmental degradation and animal welfare issues, is that prices can be depressed by overproduction when extensive tracts of land are used for production – despite the intense nature of agricultural practices.  Low prices do not reflect the actual price of food production and can result in poor market results.  It can also be argued that because of the extremely low price of food, it is a commodity that is taken for granted and often wasted – especially in the western world.

the green revolution

There is no doubt about it – there are a lot of people in the world: more than 7 billion. The sheer number of humans is probably even too much for our brains to process. Still, we’re all here and more people are coming joining the global population and every day.

Feeding so many people is a daunting task. So much so that food security is one of the most prominent issues facing the world today – despite the fact that output is greater than ever before. Successful increases in output are retarded by issues with food waste, problems with logistics and the unequal distribution of resources. However, the biggest issue preventing lasting change is the use of unsustainable production practices like monoculture, the irrigation of arid and/or semi-arid locations and high chemical inputs. For true food security to be achieved alternatives that are better adaptable to dynamic conditions are required.

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Norman Borlaug   Photo credit: nytimes.com

That is not to say that the evolution of the current system is not a biological and technological wonder.  It is a result of the Green Revolution which started the 1940s. It was during this time that Norman Borlaug, a plant breeder from the University of Minnesota, developed a high yielding wheat variety that revolutionized crop production throughout the world. The new varieties were not sensitive to hours of sunlight each day which allowed farmers to grow wheat anywhere, had more above ground mass which increased yields and produced shorter plants so that more of the plant’s energy could be focused on the usable grain production.

greenrevolution2
A comparison of dwarf and full-size wheat varieties Photo credit: http://www.lsuagcenter.com

These genetic improvements coupled with the use of newly developed irrigation systems, altered farm management techniques, hybrids and chemical pesticides and fertilizers resulted in unprecedented increases in output. For example, following the introduction of high-yielding wheat, Mexico was able to go from importing half its wheat in 1944 to exporting a 1/2 million tons of wheat in 1964. The success was so great that shortly after high producing rice varieties (with IR8 being the most notable) were introduced in other places throughout the world. The increase is estimated to be so great that these changes are credited with saving more than a billion people from starvation. It is also credited with allowing the population to continue to balloon out of control.

IR8
Photo credit: yubanet.com

Depending on the person, this is a good thing or a bad thing. Many find that humans are the best thing in the world and that continued population growth can result in improved economic climates, expanded intellectual capital and ultimately an overall betterment of the world. Others see the human presence as a burden that the world cannot truly bear. With a continuing world hunger crisis and severe weather conditions across the globe, it is hard to argue for the former.

Still, continuing efforts are being made to improve the genetic potential of seeds. There are 16 centers throughout the world focusing on the continuing development of improved crops including maize, sorghum, and beans. Unfortunately, this has led to a rapid decrease in genetic diversity and it has resulted in plants that are only able to survive with human intervention and high inputs. This has and will continue to cause serious issues as a result of droughts, floods, pests and/or disease (ex. bananas). Furthermore, many of the inputs used are non-renewable (fossil fuel, water). There are also rapidly changing consumer demands as third world countries develop and demand lifestyle choices comparable to those enjoyed by westerners (ex. higher rates of meat consumption), environmental degradation concerns, a limited amount of arable land, and unchecked population growth threatens food security.

To address these issues, there is a call for a second Green Revolution that is based on sustainability. The new revolution is aimed at efforts to reduce dependence on synthetic inputs and reduce the use of non-renewable water sources. Success in this respect can be achieved with the use of nitrogen fixing cover crops, crop rotation, alternative cropping styles, reduced tillage and farm diversification. There is also a need for a Green Revolution in Africa in order to focus efforts on improving the output of common crops grown on the continent. This would also help to reduce the yield gap that plagues many African countries.