HRT 403 - Postharvest Handling of Horticulture Crops

What are physiological disorders?

Breakdown of tissue not caused by disease organisms or mechanical damage.

What factors can induce physiological disorders?

Preharvest and postharvest factors.

Name two preharvest factors that can cause physiological disorders.

Boron and calcium deficiencies.

What are some postharvest factors affecting physiological disorders?

Temperature, humidity, gaseous composition of storage atmosphere.

What is Bitter Pit?

A calcium deficiency disorder in apples.

What is Blossom End Rot?

A calcium deficiency disorder in tomatoes.

How can calcium-related disorders be controlled?

By selecting resistant varieties, applying calcium sprays, and harvesting at the right maturity.

What are the two phases of low boron disorders in fruits?

External cork (surface spots) and internal cork (lesions in the core).

What is a common control measure for boron deficiency?

Application of borax sprays in the orchard.

What is Superficial Scald?

A disorder characterized by shiny black discoloration of apple epidermis.

What causes Superficial Scald?

Oxidation of farnesene in cold storage.

What treatment can be used for Superficial Scald?

Use of antioxidants and drenching/spraying with DPA.

What is Carbon Dioxide Injury?

Injury occurring in commodities kept in CA storage or poorly ventilated vehicles.

What factors influence the degree of Carbon Dioxide Injury?

Cultivar, temperature, oxygen, and condition of the fruit.

What are symptoms of external carbon dioxide injuries in apples?

Brown, roughened lesions on the skin.

What are symptoms of internal carbon dioxide injuries in apples?

Brown necrotic cortex or core tissue.

What is the role of the cuticle in plant defense?

It acts as the first line of defense against pathogen infection.

What is the significance of the cell wall in plant defense?

It helps defend against infection; firmer cell walls are less susceptible to pathogens.

What is the primary method of spread for most fungal pathogens?

Asexual spores called conidia.

What is the importance of preharvest control in pathogen management?

Prevention is more effective than treatment.

What does IPM stand for?

Integrative Pest Management.

What is the focus of Integrative Pest Management?

Long-term prevention of pests using a combination of techniques.

What are some mechanical/physical controls in pest management?

Screens, temperature control, CA, MAP.

What are some chemical controls in pest management?

Sanitizers and fungicides.

What are some biological controls in pest management?

Predators, parasites, and pathogens.

What are cultural control measures in pest management?

Using good storing varieties and reducing harvest damage.

What is the role of specialized metabolites in plant defense?

They can be toxic to microorganisms.

What can cause the defense of a plant to be compromised?

Ruptured epidermis, senescence, and loss of turgor pressure.

What is the mechanism of attack for pathogens?

Nesting and latency.

What is the significance of the host's structure in defense?

A strong cell wall and waxy cuticle help prevent pathogen entry.

Why is knowledge of the pathogen and host relationship important?

It is essential for effective management of diseases.

What is more effective than treatment after infection?

Prevention is far more effective and efficient.

What can consuming infected produce cause?

It could cause consumers to fall ill.

What is the impact of phytosanitary problems on international trade?

They limit free trade despite agreements like GATT.

What happens if a pest becomes established in a new location?

Exports from that area may face movement restrictions.

What is the annual damage caused by exotic pests in the US?

It exceeds tens of billions of dollars.

What is Probit 9 treatment?

It requires 99.9968% efficacy, meaning only 3 survivors in 100,000 insects.

What is the role of the International Plant Protection Convention?

It establishes universal standards for pest management and trade.

What is the mission of USDA APHIS?

To protect and promote US agriculture.

What was Japan's zero tolerance policy regarding imported cherries?

It required methyl bromide fumigation due to codling moth larvae found in 1997.

What is a systems approach in pest management?

It involves multiple layers of protection instead of relying on a single treatment.

Name a major insect pest affecting crops.

Codling Moth.

What are common postharvest treatments for insect pests?

Washing, brushing, fumigation, temperature modification, irradiation, and controlled atmosphere.

What is a key feature of postharvest treatment?

It must meet quarantine standards while maintaining product quality.

What is Methyl Bromide known for?

It is an extremely effective general biocide but is an ozone depletor.

What is the significance of Phosphine in pest control?

It is used as a fumigant in grain storage and horticulture crops.

What is the challenge with cold treatment for tropical crops?

Tropical crops are often highly susceptible to chilling injury.

What is the purpose of heat treatments in pest management?

They can kill pests and can incorporate fungicides.

How does irradiation affect insect pests?

It breaks chemical bonds in DNA, rendering them sterile.

What is the significance of specific gravity in potatoes?

It measures solids to water and is important for determining bulking rate.

What are the two types of stress affecting potato crops?

Abiotic (non-living) and biotic (living) stress factors.

What is the consequence of abiotic and biotic stress on potatoes?

It reduces the conversion of sugars into stable starch.

What is a mature potato tuber composed of?

20% dry starch and 80% water.

What is the role of nighttime cooling air in potato storage?

It helps cool potatoes, extending the storage season.

What is the primary use of essential oils in pest management?

Some function as natural pest deterrents.

What is the importance of extensive research before adopting pest control protocols?

To ensure correct dosage and duration to prevent quality loss.

What is the significance of the 'many little hammers approach' in pest management?

It combines multiple methods for effective pest control.

What is the purpose of using herbicide in potato harvesting?

To create uniform maturation of the potatoes.

Why should potatoes not be washed before storage?

Washing increases the spread of pathogens.

What is the recommended storage temperature for potatoes to reduce pathogens?

50°F.

What are the three phases of storing potatoes?

Curing, Holding, and Warming.

What is the temperature range for the curing phase of potato storage?

54-56°F for a few weeks.

What happens to potatoes during the warming phase?

Cold sweetening occurs, which increases sucrose levels and can negatively affect chipping quality.

At what temperature does dormancy break for potatoes?

54°F.

What is senescence sweetening in potatoes?

The increase in sucrose and glucose concentration as potatoes age, affecting their usability.

How does a good growing season influence postharvest potato quality?

It ensures a higher quality starch to sugar ratio, reducing the need for monitoring postharvest.

What is the importance of segregation in organic postharvest handling?

To prevent co-mingling of organic and conventional produce.

What does the National Organic Program provide?

Standards for organic postharvest handling.

What is a significant challenge in organic postharvest practices?

Fewer tools available to reduce postharvest pressures compared to conventional methods.

What is OMRI?

A body that analyzes and approves substances for use in organic agriculture.

What is the maximum allowable chlorine residue in organic produce washing?

Less than 4 ppm.

What is the restriction on ethylene use in organic postharvest handling?

It is restricted because it is synthetically derived, except for ripening tropical fruits.

What are some physical means allowed for quarantine treatments in organic produce?

Heat treatments, cold treatments, or a combination with controlled atmosphere (CA).

What are common reasons for postharvest losses in developing countries?

Inadequate harvesting procedures, inferior packaging, lack of precooling facilities, and poor infrastructure.

What is the 'pot in pot' system used for?

It is an evaporative cooler technology used in Nigeria to store produce.

What is the impact of poor product segregation in postharvest handling?

It can lead to increased spoilage and lower quality of produce.

What is the significance of maintaining high humidity in potato storage?

To prevent dehydration of the bottom layers of potato piles.

What chemical can be applied to reduce sprouting in stored potatoes?

Chloropropham or Ethylene.

What happens to glucose levels as sucrose concentration increases in stored potatoes?

Glucose levels also increase, indicating older potatoes.

What is the effect of a warm growing season on potato maturity?

It can lead to older maturity levels, reducing storage time.

What is the role of essential oils in organic potato storage?

They are important for sprout inhibition.

What are the storage temperature ranges for the holding phase of potatoes?

38-52°F, depending on the variety.

What is the consequence of high sugar contents in potatoes intended for chipping?

High sugar contents are detrimental to chipping quality.

What are some proposed interventions to improve food safety?

Improved containers, field packing, curing, sanitation, ripening practices, small scale food processing methods, education, and effective insect control.

What is the purpose of improved containers in food safety?

To avoid overfilling and prevent bruising of fruit when stacked.

What is a key feature of improved field packing?

Providing shade by packaging produce under roofs.

What is the significance of ethylene in ripening practices?

Ethylene is used in aerosol cans to control ripening.

What is a small-scale food processing method developed by UC Davis?

Chimney and drying system.

What are low cost/energy cooling methods mentioned?

Pot in pot designs, evaporative forced air cooling, hydro cooling with well water, solar powered evaporative cooling systems.

What is the importance of temperature control in postharvest handling?

Control is essential for long-distance shipping and maintaining product quality.

What is the Q10 concept in relation to respiration?

The rate of reactions increases with temperature, often doubling for every 10 ºC increase.

What is pre-hardening in the context of chilling sensitive crops?

Exposing crops to temperatures just above the breakpoint to develop tolerance to lower temperatures.

How does ethylene affect plant storage?

Many plants are sensitive to ethylene, which can accelerate senescence; it is important to separate ethylene producers from sensitive plants.

What are some treatments to block ethylene action?

1-MCP and silver thiosulfate solutions.

What is the trade-off when shipping well-moistened plants?

They are heavier and more prone to disease, while dry plants may desiccate.

What is the general rule for containers used in postharvest handling?

Use plastic containers and clean them with bleach or chlorine.

What are preservation solutions used for in postharvest handling?

To maintain low pH, add sugars, and include antibacterial chemicals to reduce bacteria growth.

What are fresh cut fruits and vegetables?

Ready-to-eat produce prepared for immediate consumer use, including cleaning, peeling, and slicing.

What challenges do fresh cut fruits and vegetables face?

Increased vulnerability to contamination and the need for higher quality due to processing.

What is one solution to improve the quality of fresh cut apples?

Breeding cultivars with low polyphenol-oxidase to reduce browning.