Fruit Crop Ecology and Management - UVM Apple Orchard

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pesticides can affect the nature and abundance of these microbes. The plant roots make up the belowground crop habitat. Mostly hidden from view, the root zone is home to a diverse array of worms, insects, fungi and bacteria. Although the large majority of soilborne organisms are beneficial or neutral toward crop plants, some cause serious problems that can limit crop productivity. In perennial plants, including most fruit crops, complex communities of microorganisms develop on roots. While some root exudates are known to attract swimming spores of water molds such as Pythium and Phytophthora, plants also have the ability to chemically promote the growth of beneficial bacteria and fungi. Some plant roots support the growth of fluorescent bacteria that preferentially bind iron, thereby making it unavailable to pathogens. Host plant resistance Plants vary in their ability to defend themselves against pest attack, with some being highly resistant and others quite susceptible. Plant defense mechanisms include physical “weapons” such as thick wax layers, tough skin, thorns and plant hairs. It is Fruit Crop Ecology and Management: Chapter 2 Most wine grapes have thinner skinned leaves than juice grape varieties, making them more susceptible to potato leafhopper damage, as shown in this photo. more difficult for leafhoppers to feed on the thick-skinned leaves of juice grape varieties than on the thin-skinned leaves of wine grape varieties. Plants also produce many kinds of defensive chemicals, such as toxins and enzymes, to ward off insect or pathogen attack. The chemical resveratrol, which occurs in grape skin and may be responsible for the human health benefits of wine consumption, also provides protection against infection by pathogenic fungi. Alkaloids in certain plant varieties are known to be lethal to insects. Some plants protect themselves by releasing odors that signal predators when a pest feeds on them. These odors help predators locate the pest and reduce pest abundance. Some varieties, even though attacked by pests as much as other plants, are less affected and therefore considered tolerant. For example, under moderate insect feeding on leaves, native juice grape varieties can still produce acceptable yields and fruit quality. Growing pest- and diseaseresistant fruit varieties is an excellent way to reduce the use of chemical or other control measures. It is often the R. Isaacs 41
42 Red stele is evident in the strawberries at right, while those planted on the left are resistant to the particular race of the disease. simplest method of pest control because the plant does all the work. Unfortunately, some pests can evolve to overcome plant resistance. Once this happens, resistant cultivars can lose their usefulness. For example, some strawberry cultivars are resistant to multiple races of the red stele fungus, but none is known to be resistant to all races. Efforts to find more durable forms of resistance to red stele have Rootstocks to the rescue Ecological concept Host plant resistance reduces pest damage. Putting it into practice Use only resistant rootstocks when planting susceptible grape varieties. Grape phylloxera is an aphidlike insect that feeds on grape roots, stunting and sometimes killing vines. This pest is so damaging that when it was inadvertently introduced into Fruit Crop Ecology and Management: Chapter 2 M. Ellis A. Schilder been unsuccessful. If available, cultivars resistant to locally prevalent races of disease should be selected for planting. In general, one should avoid cultivars that are highly susceptible to the disease. This problem is a bigger issue with perennial plantings that will be in place for many years. Seasonal and longterm changes in habitat suitability A plant is often susceptible to a pest or disease only during a certain period in its development. Usually younger, succulent tissues are more susceptible to pest attack. However, older tissues sometimes lose the defense mechanisms inherent in younger tissues and then provide fertile ground for pest and pathogen activity. The fire blight bacterium prefers to infect young, fast- Europe from the United States in the 1860s, it nearly destroyed the French wine industry. The vines were saved by imported American rootstocks, which are resistant to phylloxera. Resistant rootstocks are still the primary method of phylloxera control. In the early 1980s, however, a biotype with the ability to colonize some resistant rootstocks appeared in California. This event has led to recent largescale replacement of vineyards with vines grafted onto other resistant rootstocks.
Page 1 and 2: Michigan State University Extension
Page 4 and 5: Fruit Crop Ecology and Management I
Page 6 and 7: Enterprise goals ◆ High quality f
Page 8 and 9: In Chapter 4, we set aside the imag
Page 10 and 11: ecology of the landscape, including
Page 12 and 13: the most important constraint influ
Page 14 and 15: temperature extremes and in seasona
Page 16 and 17: R. Zoppolo/D. Stefanelli R. Zoppolo
Page 18 and 19: cultural factors — such as crop l
Page 20 and 21: grafting compatibility that will in
Page 22 and 23: set and production. Timing of chemi
Page 24 and 25: 6 CO2 So So r en gy 6 H2O Organic a
Page 26 and 27: Two organisms are better than one.
Page 28 and 29: Plants rely on microbes to recharge
Page 30 and 31: quences. Too much nitrogen results
Page 32 and 33: conditions. Residues of legumes suc
Page 34 and 35: protected with mulch. In a mature p
Page 36 and 37: or yield to a level affecting profi
Page 38 and 39: material because of their distinct
Page 40 and 41: Single and multicycle pathogens Dis
Page 44 and 45: growing shoots. In contrast, the fu
Page 46 and 47: Ecological concept Wounds predispos
Page 48 and 49: Adults and larvae generally are ada
Page 50 and 51: After a certain period, in which sy
Page 52 and 53: How pathogens cause disease Spore l
Page 54 and 55: alance of the community is disrupte
Page 56 and 57: Parasites A parasite lives in, on o
Page 58 and 59: W. Yang Mycorrhizael hyphae (the th
Page 60 and 61: sources of sugar. For example, Tric
Page 62 and 63: Pesticide impacts on the community
Page 64 and 65: Such differences lead to significan
Page 66 and 67: soilborne pathogens. Moisture, temp
Page 68 and 69: A. Schilder The causal agent of lea
Page 70 and 71: y ascospores are typically more num
Page 72 and 73: track of GDD accumulation based on
Page 74 and 75: indicates that leaf wetness can var
Page 76 and 77: accumulations were predicted to inc
Page 78 and 79: alance these positive and negative
Page 80 and 81: In the foreground, a ground cover o
Page 82 and 83: Ecological concept Insects can migr
Page 84 and 85: their growers keep costs as low as
Page 86 and 87: A 1997 Food Marketing Institute stu
Page 88 and 89: Working with local governments and
Page 90 and 91: Direct farm marketing is not easy.
Page 92 and 93:
Human resources: You can’t raise
Page 94 and 95:
Like many fruit farmers, the Gregor
Page 96 and 97:
Richard H. Lehnert, Joy N. Landis,
Page 98 and 99:
But the future of the commercial ma
Page 100 and 101:
sustainable, but they are the best
Page 102 and 103:
J Japanese beetle 46, 47, 67, 76 L
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Fruit Crop Ecology and Management - UVM Apple Orchard

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