22 Slices
Medium 9781780645346

Chapter 9 Vegetable Safety

Welbaum, G.E. CAB International PDF

9

Vegetable Safety

Pesticide Residues

Monoculture production systems were established over 100 years ago to allow greater mechanization to help farmers grow larger acreages with less labor.

Monoculture systems are more prone to pest outbreaks because the ecological balance is disturbed

(Altieri, 1999). To counter outbreaks of harmful insects, plant diseases, and weeds that occur in monoculture production systems, pesticides were developed to provide control by spraying with minimal labor. Pesticide usage increased steadily from the 1940s through the 1970s as new chemicals were developed for pest control for a wide variety of reasons (MacIntyre, 1987). However, by the 1970s and 1980s, there was increasing public concern about pesticide residues on vegetables and their negative effects on human health. A series of high profile cases that resulted in serious illness and death were traced to pesticide residues on vegetables and focused public attention on this issue. For example, poisoning caused by improper use of the chemical aldicarb (Temik) 2-methyl-2-(methylthio) propionaldehyde-O-(methylcarbomoyl)oxime caused illness after eating contaminated watermelons and cucumbers (Goes et al., 1980; Green and Wehr, 1987). The largest pesticide-related foodborne outbreak in the

See All Chapters
Medium 9781780645346

Chapter 12 Family Asteraceae

Welbaum, G.E. CAB International PDF

12

Family Asteraceae

Origin and History

LETTUCE, ENDIVE, AND CHICORY

Asteraceae is a very large and widespread family with more than 23,000 species, spread across

1,620 genera (Jeffrey, 2007). Family members are annual or perennial herbs, many are weeds or wild flowers, and a few are woody but are not usually classified as trees. Asteraceae contains many familiar ornamental plants including aster, marigold, calendula, daisy, chrysanthemum, dahlia, and zinnia and medicinal plants including grindelia, echinacea, yarrow, and many others

(Duke, 2013).

The Latin name “Asteraceae” is derived from the

Greek word for “star”. Compositae is an older family name that still appears in the literature and is derived from the word composite, which refers to the characteristic inflorescence found in only a few angiosperm families.

A characteristic of many Asteraceae species is milk-like latex contained in its tissues. Latex from dandelion roots can be used as a source of rubber. During World War II, some European nations grew dandelions for rubber production when tropical sources were unavailable. Today, several species of dandelion, most particularly

See All Chapters
Medium 9781780645346

Chapter 3 Vegetable Seeds and Crop Establishment

Welbaum, G.E. CAB International PDF

3

Vegetable Seeds and Crop

Establishment

Introduction

Most vegetable crops are grown from seeds and not vegetatively propagated. A seed can be defined as

“an immature plant in an arrested state” produced through sexual reproduction. If a plant produces seeds that germinate “true-to-type” and grow rapidly, it is cheaper, more efficient, and usually faster to propagate the crop by seed. True-to-type simply means that the plant that results from a seed has the same traits and appearance as the plant that produced the seed.

Vegetables that do not grow true-to-type from seed or that are difficult to propagate from seed such as potato, sweetpotato, or globe artichoke are vegetatively propagated. Vegetative propagation is a form of asexual reproduction of a plant where the stems, leaves, and roots, or other tissue not involved in reproduction are rooted. With vegetative propagation, the new plant is a clone that is genetically identical to the parent.

Seeds produced through tissue culture are sometimes called synthetic seeds. Synthetic seed can be defined as the artificial encapsulation of somatic embryos, shoot buds, aggregates of cells, or any tissues that have the ability to form a plant (Fujii et al., 1987). Synthetic seeds have been produced commercially but make up a small percentage of the commercial vegetable seeds sold in the world.

See All Chapters
Medium 9781780645346

Chapter 22 Family Agaricaceae

Welbaum, G.E. CAB International PDF

22

Family Agaricaceae

MUSHROOMS

Introduction

Mushrooms are a very important world crop that fit the definition of a vegetable given in Chapter 1.

However, unlike the other vegetables we have discussed thus far, the mushroom is not a plant but a fungus (Carluccio, 2003). So mushroom-production practices are unique compared to the traditional vegetables discussed in previous chapters.

Mycology

Mushrooms are heterotrophic organisms, which means they must find and absorb food from their environment. This is contrast to most other vegetables, which are autotrophic plants that can fix carbon dioxide (CO2) from the atmosphere via photosynthesis. Mushrooms must acquire carbon from sources other than gaseous atmospheric CO2, so organic matter (rather than soil) is required as substrate for mushrooms to acquire their nutrients and support mycelial growth (Chang and Hayes,

1978; Del Conte et al., 2008). The types of organic matter needed vary widely with the kinds of mushrooms grown (Carluccio, 2003).

Types of Cultivated Mushrooms

See All Chapters
Medium 9781780645346

Chapter 5 Irrigation of Vegetable Crops

Welbaum, G.E. CAB International PDF

5

Irrigation of Vegetable Crops

Introduction

Irrigation may be defined as the science of applying water to the land or soil. Irrigation has many diverse uses, including the growing of agricultural crops, maintenance of landscapes, revegetation of disturbed soils in dry areas and during periods of inadequate rainfall. Additionally, irrigation also may provide frost protection for vegetable crops (Snyder and Melo-Abreu, 2005). In contrast, production that relies only on direct rainfall is referred to as rain-fed or dryland vegetable farming. Successful vegetable production in many regions is dependent upon farmers having sufficient water for irrigation. Water scarcity is a critical constraint to farming in many parts of the world.

Arid regions frequently suffer from physical water scarcity. Physical water scarcity is where there is insufficient water to meet all demands, including those needed for ecosystems to function effectively.

Symptoms of physical water scarcity include environmental degradation and declining groundwater.

See All Chapters

See All Slices