- Author: Steve Tjosvold and Steve Koike
Diseases, disorders and other plant problems are critical concerns for the wholesale nursery. These include biotic problems — caused by living organisms such as pathogens, nematodes, and insects and other arthropods — as well as abiotic problems — caused by factors such as temperature and moisture extremes, mechanical damage, chemicals,
nutrient deficiencies or excesses, salt damage and other environmental factors. Many plant problems, especially biotic problems, if not recognized and controlled early in their development, can result in significant economic damage for the producer. Therefore, timely and accurate diagnoses are required so that appropriate pest and disease
management options and other corrective measures can be implemented.
Definition of Plant Diagnosis and Steps
Diagnosis is the science and art of identifying the agent or cause of the problem under investigation. When one renders a diagnosis, one has collected all available information, clues and observations and then arrives at an informed conclusion as to the causal factor(s). Hence, plant problem diagnosis is an investigative, problem-solving process that involves the following steps:
- Ask and answer the appropriate questions to define the problem and
obtain information that is relevant to the case under investigation.
- Conduct a detailed, thorough examination of the plants and production areas.
- Use appropriate field diagnostic kits and lab tests to obtain clinical information on possible causal agents and factors.
- Compile all the collected information and consult additional resources and references.
- Finally, make an informed diagnosis.
Throughout this process compile all notes, observations, maps, laboratory results, photographs and other information. This compilation will be the information base for the present diagnosis and can also be a useful resource for future diagnostic cases. Keep an open mind as the information is analyzed and do not make unwarranted assumptions.
Distinguishing Abiotic and Biotic Problems
The first step is to determine whether the problem is caused by an infectious agent, and this can be difficult. Plant symptoms caused by biotic factors such as infectious diseases and arthropod pests are oftensimilar to damage caused by other factors. Leaf spots, chlorosis, blights, deformities, defoliation, wilting, stunting and plant death can
be common symptoms of both biotic and abiotic problems; therefore, the presence of these symptoms does not necessarily mean the problem is a disease. Some general guidelines for distinguishing abiotic and biotic
problems follow and are summarized in table 1.
Table 1 DISTINGUISHING ABIOTIC AND BIOTIC PROBLEMS |
||
Characteristics |
Abiotic |
Biotic |
Hosts |
often affects several species or plants of various ages |
often affects one species or cultivar of the same age |
Pattern of plant symptoms |
often related to environmental or physical factors or cultural practices; may be regular or uniform |
often initially observed in random or irregular locations |
Rate of symptom development |
relatively uniform, extent of damage appears similar among plants |
relatively uneven, time of appearance and damage severity varies among affected plants |
Signs |
no evidence of the kinds of pests or pathogens known to cause the current symptoms |
presence of insects, mites, |
Spread |
is not infectious, is not progressive, commonly caused by one incident and does not spread |
infectious, spreads on host over time if environmental conditions are suitable |
Recurrence |
possibly previously associated with current or prior environmental conditions or cultural practices |
possibly caused by pests that |
Adapted from Table 18, ANR Pub 3420 |
Biotic problems. Identifying biotic problems is sometimes facilitated if signs of a pathogen, primarily the growth of a fungus, are present. The most obvious examples of such signs are the mycelium and spores produced by rusts and powdery and downy mildews. However, in other cases nonpathogenic fungican grow on top of damaged plant tissues and appear to be signs of a pathogen, resulting in possible misdiagnoses.
Biotic problems often affect one species or cultivar of the same age and typically are initially observed in random or irregular locations; symptoms appear at varying times, and severity varies among affected plants. Biotic problems are infectious, spreading when environmental conditions are favorable, and may be associated with pests that have affected the crop. This infectious aspect is important, as biotic diseases will many times be progressive and continue to affect
additional tissues and more plants.
Abiotic problems. In contrast to biotic factors, abiotic problems often affect several species or plants of various ages; typically, damage is relatively uniform, doesn't spread and is often not progressive. Abiotic problems are not associated with pests. They are often caused by a single incident and are related to environmental or physical factors or cultural practices. Once the responsible factor has dissipated and is no longer affecting the plant, the plant may grow out of the problem and develop new, normal appearing foliage.
Diagnosing Biotic Problems
Infectious diseases. To confirm if a problem is caused by a pathogenic fungus, bacterium, nematode, or virus, it is often necessary to have symptomatic tissues analyzed by a trained horticulturalist or plant pathologist. Such experts will attempt to microscopically observe the agent and recover it, if culturable, through isolation procedures. Lab analysis is particularly important to determine if multiple pathogens are infecting the plant. A downside is that obtaining a diagnosis from lab analysis is not a fast process. However, quick test kits (fig. 1A) are available that can be used to rapidly identify many common diseases in the field.
A B
Fig.1. Diagnosing biotic
problems. Plant pathogens can sometimes be rapidly diagnosed using
commercially available quick tests, such as these test strips for
viruses (A). Arthropod pests such as Cuban laurel thrips (shown here on Ficus) cause feeding damage, which can help in pest identification (B). Photos: S.T. Koike (A), J. K. Clark (B).
It is worthwhile to emphasize that diagnosing plant diseases requirescareful examination of the entire plant specimen. Symptoms on leaves, stems, or other above ground plant parts might lead one to suspect that afoliar pathogen is involved. However, these symptoms could also resultif the roots are diseased. Therefore, it is important to conduct a
complete examination of the symptomatic plant.
Because biotic diseases are caused by living microorganisms, the collecting and handling of samples is particularly critical. Samples that are stored for too long a time after collecting or that are allowedto dry out or become hot (if left inside a vehicle, for example) will sometimes cause the pathogen in the sample to die, making pathogen recovery and identification impossible. Plants that have been diseased for a long time and that are in the late stages of disease development will often be colonized by nonpathogenic saprophytic organisms. If these tissues are collected, it will be difficult to recover the primarypathogen of concern because of the presence of these secondary decay organisms. Root samples should be collected carefully as diseased rootsare sometimes difficult to dig out of the potting mix or soil, are
usually colonized by the pathogen as well as secondary agents, and are very sensitive to high temperatures and drying conditions.
Arthropod and other invertebrate pests. Insects,mites, slugs and snails cause damage while feeding on the plant (fig. 1B). Feeding damage is usually associated by the type of feeding characteristics and mouthparts of the insect or pest. For example, mites and insects such as whiteflies, aphids and mealybugs have tubular sucking mouthparts that suck plant fluids, causing buds, leaves, or flowers to discolor, distort, wilt, or drop. Thrips have rasping mouthparts that result in dried out, bleached plant tissue. Caterpillars, weevils, snails and slugs have chewing mouthparts that
make holes and cuts in foliage or flowers. They can also prune plant parts and sometimes consume entire plants.
If present, these pests are visible with the naked eye, a 10 X hand lens, or stereomicroscope, all depending upon their size. An assessment of whether the identified arthropod or invertebrate matches the plant damage it is associated with must be determined. Sometimes the identified arthropod or invertebrate may not be the sole problem or
could, in fact, be a beneficial organism or insignificant pest.
Aphids, whiteflies, thrips, leafhoppers and some other insects that suck plant juices may vector pathogens such as viruses and phytoplasmas (and to a lesser extent fungi and bacteria). They can feed on infected plants, acquire the pathogen, feed on healthy host plants and transmit the pathogen to the new host. The insects do not necessarily have to bepresent in large numbers to cause a significant disease outbreak. The insect vectors are not always present at the same time the disease symptoms are being expressed.
The excrement and byproducts from these pests can also provide clues that the pests have been or are actively present. Caterpillars and other chewing pests produce dark excrement or droppings. Greenhouse thrips and plant bugs produce dark, watery, or varnish-like droppings onfoliage. Aphids, whiteflies, soft scales, and some other sap-sucking insects excrete excess plant fluids as honeydew, a sticky sap, which provides a medium for the growth of sooty mold.
Diagnosing Abiotic Problems
Nutrient deficiencies and toxicities. Nutrientdeficiencies and toxicities reduce shoot growth and leaf size, cause leaf chlorosis (fig.2A), necrosis and dieback of plant parts. However, nutrient deficiencies cannot be reliably diagnosed on the basis of symptoms alone because numerous other plant problems can produce similarsymptoms. There are general symptoms that can be expressed by deficiencies of nutrients but usually leaf and/or soil samples are
needed to confirm the problem.
A B
Fig. 2. Examples of abiotic problems. Iron deficiency on sweet gum (Liquidambar styracifolia) showing interveinal chlorosis (A). Chorotic spots on Hedera caused by a miticide application at a higher dosage rate than specified on the pesticide label (B). Photos: E. Martin (A), S. A. Tjosvold (B).
Herbicide, insecticide and fungicide phytotoxicity. Herbicidesused to control weeds in crops or in non-cropped areas sometimes injureornamental crops when they are not used in accordance with label instructions. Examples include when an herbicide is used in or around sensitive non-target crops, when an herbicide rate is increased above tolerable limits, or when an applicator makes a careless application. By understanding the mode of action of the herbicide, one can determine if the symptom fits an herbicide application. Herbicide detection in affected plants is possible with the help of a specialized laboratory but the analysis can be expensive. To minimize the cost of testing, the laboratory will need to know the suspected herbicide or its chemical group to narrow the analysis. Pesticides and fungicides occasionally cause obvious plant damage.
Symptoms can vary widely. Generally, flower petals are more susceptible to damage from pesticide applications than are leaves. The younger and more tender the leaves the more susceptible they are to pesticide applications. Hot weather can exacerbate the damage the chemicals cause. Pesticides that have systemic action can have a more profound effect. Some active ingredients can adversely affect the photosynthetic mechanism or other physiological processes and can resulti n a general leaf chlorosis, interveinal chlorosis, leaf curling and stunting. Emulsifiable concentrate (EC) formulations, soaps and oils can adversely affect the waxy surface layer that protects the leaf from desiccation. Applications with these products can result in the loss ofthe shiny appearance of a leaf, leaf spotting and necrosis. Pesticidesapplied as soil drenches can cause poor germination, seedling death, or
distorted plant growth.
Check label precautions against use on certain species. Make sure thepesticide is not applied more frequently or at a higher rate (fig. 2B) than recommended, or that the pesticide is not mixed with incompatible pesticides. When in doubt as to whether the plant species is sensitive to the pesticide, spray a few plants and observe them for several days to a week for any signs of damage before spraying any more of the plants.
Physiological and Genetic Disorders
There are numerous disorders that can occur because of environmental extremes — too much or too little of an environmental element such as light, temperature, water, or wind. Sunburn is damage to foliage and other herbaceous plant parts caused by a combination of too much light and heat and insufficient moisture. A yellow or brown area develops on foliage, which then dies beginning in areas between the veins. Sunscaldis damage to bark caused by excessive light or heat. Damaged bark becomes cracked and sunken. Frost damage causes shoots, buds and
flowers to curl, turn brown or black and die. Hailstones injure leaves,twigs, and in serious cases even the bark. Chilling damage in sensitive plants can cause wilting of foliage and flowers and development of dark water-soaked spots on leaves that can eventually turn light brown or bleached, and die. Physical and mechanical injury can occur when plants are mishandled during transport or routine cultural practices. Wounds might serve as entry sites for plant pathogens and can attract boring insects to woody stems.
In closed environments such as greenhouses and nursery storage areas,plants can be exposed to toxic levels of ethylene gas. Sources of ethylene include improperly functioning or unvented greenhouse heaters; exhaust from engines of forklifts and vehicles; cigarette smoke; damaged, decaying, or dying plants; and ripe or decaying fruit. Toxic levels of ethylene gas can cause premature abscission of flower buds, petals (fig. 3) and leaves. Other symptoms include wilted flowers, chlorosis, twisted growth or downward bending of stems and leaves and undersized or narrow leaves.
A B
Fig. 3. Poor air quality can
lead to physiological disorders. Shattering (petal drop) on geranium was
caused by plant exposure to low levels of ethylene in the greenhouse or
during postharvest storage (A). Yellowish and brownish patches on
Japanese maple leaves are damage caused by ozone (B), an outdoor air
pollutant. Photos: J. K. Clark.
Outdoors, exposure of nursery plants to air pollutant gases such as ozone (fig. 3), carbon monoxide, nitrous oxides and sulfur dioxide can cause damage. Typical symptoms vary widely, but include slow growth anddiscolored, dying, or prematurely dropping foliage. Damage is often found where plants are located near sources of polluted air such as near
freeways or industries or where weather and topography concentrate the pollutants.
Sometimes plants or plant shoots exhibit an unusual and sudden changeof color producing discrete markings of variegation. For example, a plant with entirely green leaves suddenly produces a shoot that has leaves with edges lacking green pigment, stripes, or blotches. A new shoot such as this is probably a chimera (fig. 4). It is produced when a genetic mutation occurs in a specific region of the growing tip resulting in a section with genetically different cells. The ostensible result of the genetic change is dependent on the arrangement of the genetically different cells in the shoot tip and their expression. This can lead to sometimes bizarre variegation forms or sometimes forms thatare quite desirable. Sometimes variegation can be caused by viruses. Viruses usually cause non-uniform chlorosis, such as mosaics, while
chimeras usually produce patterned forms such as variegation of color onleaf margins, stripes, or complete loss of pigment. Some viroids may also cause bleaching of pigments in leaves; such symptoms, however, are generally produced throughout the plant and are not restricted to a single shoot. Some nutrient disorders can cause variegation but these disorders usually do not arise from a specific shoot as with chimeras.
Fig. 4. Genetic disorder.
Growing points with variegated leaves can sometimes arise spontaneously
from some species such as this Origanum. Genetic variants such as this are sometimes confused with plants with virus disease or nutrient deficiency symptoms. Photo: S. A. Tjosvold.
Steve Tjosvold is Environmental Horticulture Advisor and
Steve Koike is Plant Pathology Farm Advisor, UC Cooperative Extension,
Santa Cruz and Monterey counties.
This article was condensed from: Diagnosing Plant
Problems, Chapter 11. In Newman, J. (ed) Container Nursery Production
and Business Management. Univ. of Calif. Agric. and Nat. Resources.
Publication 3540. Richmond, CA.
References
Boxer P, Sandmann G. 1989. Target sites of herbicide action. Boca Raton, FL: CRC Press.
Costello L, Perry E, Matheny N, Henry M, Geisel P. 2003. Abiotic
disorders of landscape plants: A diagnostic guide. Oakland: University
of California Division of Agriculture and Natural Resources Publication
3420.
Derr JF, Appleton BL. 1988. Herbicide injury to trees and shrubs: A
pictorial guide to symptom diagnosis. Virginia Beach, VA: Blue Crab
Press.
Dreistadt SH. 2001. Integrated pest management for floriculture and
nurseries. Oakland: University of California Division of Agriculture and
Natural Resources Publication 3402.
Eagle, DJ. 1981. Diagnosis of herbicide damage to crops. New York, NY: Chemical Publishing Co.
Grogan RG. 1981. The science and art of plant disease diagnosis. Annual Review of Phytopathology 19:333–351.
Ratzinger EJ, Mallory-Smith C. 1997. Classification of herbicides by
the site of action for weed resistance management strategies. Weed
Technology 11:384–393.
Schubert TS, Breman LL. 1988. Basic concepts of plant disease and how
to collect a sample for disease diagnosis. Plant Pathology Circular No.
307. Florida Department of Agriculture and Consumer Services, Plant
Pathology Circular No. 307.
Sharma MP. 1986. Recognizing herbicide action and injury. Alberta Environmental Centre, Alberta Agriculture. Agdex 641–647.
Shurtleff MC, Averre CW. 1997. The plant disease clinic and field
diagnosis of abiotic diseases. St. Paul, MN: American Phytopathological
Society Press.
Stewart TM, Galea VJ. 2006. Approaches to training practitioners in
the art and science of plant disease diagnosis. Plant Disease
90:539–547.
Tickes B, Cudney D, and Elmore C. 1996. Herbicide injury symptoms.
Tucson, AZ: University of Arizona Cooperative Extension Publication No.
195021.
- Author: Sonia Rios
- Author: Niamh Quinn
- Author: Eta Takele
Wild pigs currently exist in 56 of California's 58 counties and can be found in a variety of habitats ranging from woodland, chaparral, meadow, grasslands and in agriculture cropping systems. Wild pigs are commonly found in the foothill areas, and they prefer areas of dense brush, however the drought has led them to encroach into orchards. Wild pigs can cause significant damage to farm and rangelands, natural resources, environmentally sensitive habitats, and property. Wild pig depredation on livestock and poultry can cause high economic loss (Choquenot et. al. 1996). Also, wild pigs can carry a number of diseases and parasites that can be transmitted to livestock, wildlife, and humans. In California, wild pigs can be carriers of Brucellosis, Cholera, Leptospirosis, Tuberculosis (Bovine, Avian, and Swine), Q fever, Trichinosis, Toxoplasmosis, Pseudorabies, and Plague (Barrett and Tietje 1993).
DESCRIPTION OF THE PEST
Domestic swine were imported to the United States by European settlers in the 1700s. Whereas Domestic swine foraged freely, eventually becoming semi-wild, or “feral” (CDFW 2017), California's wild pigs were descendants of the Eurasian wild boar, introduced to Monterey County, California in the 1920s. The physical characteristics of California's wild pigs vary significantly throughout the state. Some exhibit the long hair and snouts, small erect ears and angular shaped bodies of their wild boar ancestors, while others have short hair, long floppy ears, and a barrel-shaped body. Colors range from solid black to red, striped, grizzled or spotted (CDFW 2017). Domestic pigs that are unmarked and roam freely are also considered to be wild pigs.
DAMAGE IN CITRUS
Cultivation operation disruption
Evidence of wild pigs' presence is obvious even if you don't see them physically. Wild pigs use their snouts to root up the ground in search of food, including plant roots, fungus, and other items. Wild pigs are omnivorous, consuming both plant and animal matter. In general, wild pigs feed on: grasses and forbs in the spring; mast and fruits in the summer and fall; and roots, tubers and invertebrates throughout the year.
Wild pigs will feed on insects and underground vegetation. This rooting behavior can disrupt parts of the orchard floors. it could lead to the trees becoming susceptible to root rot diseases that could spread throughout the grove. They are also known to eat fruit off of the lower branch scaffolds. Pigs will contribute to erosion which can affect water quality and also create large uneven basins, or wallows in moist soil during hot weather. Both rooting and wallows can disrupt the application of irrigation water by ruing or displacing irrigation equipment and resulting pools can become breeding habitat for mosquitoes.
Food safety
Wild pigs can also create a food safety issue. Growers are now required to show a Food Safety Good Agricultural Practices for California Citrus Growers (GAPs). This practice is focused on the grower's particular role in providing safe citrus fruits for consumers. The grower should assess the impact of domestic, livestock and wild animal activity for potential pathogen contamination of the grove and fruit. The assessment should include the extent of intrusion, nearness to the grove, proximity to harvest and other relevant factors. Based on the assessment, the grower should put into place measures to exclude domestic animals and minimize the intrusion of wildlife into the grove.
- The grower should monitor the grove and adjacent land for evidence of animal activity and the potential for contamination of fruit or equipment.
- The grower should return bins to packers if there is evidence of contamination.
- When the assessment or monitoring indicates possibility of contamination with pathogens, the grower should take action as needed to minimize potential for contamination of the fruit and to prevent the harvest of any potentially contaminated fruit
Pre-Harvest
- The grower should perform a documented evaluation of the grove environment for changes that may be likely to result in contamination of the citrus fruit with pathogens. Evaluation should include inspection for:
o Evidence of animal intrusion such as downed fences, presence of live or dead animals, animal tracks or animal feces. If animal intrusion is detected, measures shall be taken to remove or prevent from harvest any potentially contaminated product.
o Presence of potentially contaminating materials (e.g. uncomposted manure, etc.) likely to pose a contamination risk to the grove to be harvested.
o Evidence that the irrigation water source and delivery system may potentially be compromised.
For more information regarding Citrus GAP: http://ccqc.org/wp-content/uploads/2009/05/Final-Food-Safety-GAP-document-_Oct-26_.pdf
MANAGEMENTClassified as a game mammal in California, wild pigs provide year-round hunting opportunity and fall under the jurisdiction of the California Department of Fish and Wildlife (CDFW). A hunting license and a tag is required to hunt wild pigs. If wild pigs are causing damage to your property, pigs can be trapped or shot, but this requires a depredation permit. Contact your local CDFW representative for further details on depredation permits (https://www.wildlife.ca.gov/Conservation/Mammals/Wild-Pig/Depredation).
Monitoring and Management Strategies
Fencing
Fencing can be extremely effective but because of costs it can be extremely prohibitive. However, on smaller scales, exclusionary fencing can be an effective option. One of the most effective designs seems to be the installation of sturdy wire mesh fencing. The bottom wire should be either tightly stretched on the ground surface or buried. The addition of an electrified wire about 6 to 8 inches off the ground is also recommended. The fence should be at least 36 inches high. Electric fencing alone has also been shown to restrict the movement of wild pigs also. Poorly designed and constructed fences will significantly increase repair and maintenance time. It is important to carefully consider the costs and benefits of fencing for pig exclusion before embarking on such a venture.
Trapping
Trapping can be an effective method of removing wild pigs from your orchard. The most commonly used traps are box traps and corral traps. Corral traps are much larger than box traps and are designed to capture multiple pigs. It is important to consider that all wild animals can be unpredictable when approaching captured pigs.
In some counties, the agricultural commissioner has trappers who can assist; other counties have contracts with USDA-Wildlife Services to assist with problematic pigs.
Toxicants and Repellents
Currently there is one toxicant registered for use on wild pigs in the United States (EPA Reg. No. 72500). This product is not currently registered for use in California. This product may only be used to control wild pigs on pastures, rangeland, forests, non-crop areas, and crop lands. This bait may only be applied in hog feeders equipped with heavy lids (8 to 10 lbs. of total weight) on bait compartments so as to limit direct access to bait by nontarget animals. This product may be toxic to fish, birds and other wildlife. Dogs and other predatory and scavenging mammals and birds might be poisoned if they feed upon animals that have eaten the bait. Wild pigs must be conditioned to accept feed from the bait dispensers and to open the weighted lids to bait compartments.
Repellents are not generally considered effective against many mammalian pests and this is also true for the management of wild pigs.
Collecting information on wild pig damage
UCANR is asking California growers and landowners to help keep track of the state's wild pigs and the damage they are causing through a new Wild Pig App. The app is available for download on Apple and Android devices and will collect information on wild pig damage throughout California. Cell service at the site of pig damage is also not required to collect the information. The information collected will be used by University of California Cooperative Extension Specialists and Advisors to learn more about wild pigs in the State.
Download the app at your App Store to participate in the wild pig damage project without the app, landowners and growers can fill out a short survey at http://ucanr.edu/wildpig2016.
Additional Resources
Barrett, R. H. and G. H. Birmingham. 1994. Wild Pigs. The Handbook: Prevention and control of wildlife damage. Cooperative Extension Division, University of Nebraska-Lincoln.
California Department of Fish and Wildlife <https://www.wildlife.ca.gov/Conservation/Mammals/Wild-Pig> Accessed: 24 July 2017.
Barrett, R. H., and W. Tietje. 1993. The wild pig in California oak woodland: ecology and economics. Conference Presentation Summaries. Univ. of California, Berkeley.
Coping with Feral Hogs. Texas A&M AgriLife Extension Service.
Feral Hog Biology, Impacts, and Eradication Techniques (PDF). 2010. USDA APHIS Wildlife Services New Mexico.
Finzel, J. A. and Baldwin, R. A., (2015) Pest Notes: Wild Pigs. UC ANR Publication 74170
Hamrick, B., M. D. Smith, C. Jaworowski, B. Strickland. 2011. A Landowner's Guide for Wild Pig Management(PDF). Publication 2659.
Jay-Russell, M. T., A. Bates, L. Harden, W. G. Miller, and R. E. Mandrell. 2012. Isolation of campylobacter from feral swine (Sus scrofa) on the ranch associated with the 2006 Escherichia coli O157:H7 spinach outbreak investigation in California. Zoonoses and Public Health. 59:314-319.
Kreith, M. 2007. Wild pigs in California: the issues (PDF). AIC Issues Brief No. 33. Agricultural Issues Center, University of California.
Sweitzer, R. A. and D. H. VanVuren. 2002. Rooting and foraging effects of wild pigs on tree regeneration and acorn survival in California's oak woodland ecosystems (PDF). USDA Forest Service General Technical Report PSW-GTR-184.
Waithman, J. 2001. Guide to hunting wild pigs in California. California Department of Fish and Wildlife, Wildlife Programs Branch.
West, B.C., A. L. Cooper, J. B. Armstrong. 2009. Managing wild pigs: A technical guide (PDF). Human-Wildlife Interactions Monograph 1:1.
- Author: Ben Faber
My dad always said that if you can learn one good thing from a meeting, it was a good meeting. Here's a webinar that might offer something good to for tree growers. Listen in and make up your mind.
Webinar: California & Chile: Opportunities for Precision Agriculture in Climate Change Adaptation and Mitigation.
Agenda & Speakers
Introduction
- Dr. Amrith Gunasekara, Science Advisor to the Secretary, CDFA
Opening Remarks
- Dr. Pablo Zamora, Associate Director, UC Davis Chile
- Marcela Rondon, Agricultural Attaché , USDA FAS
Panel 1: Innovation in precision agriculture
- Dr. Tom Shapland, Co-founder and CEO, Tule Technologies
- Andreas Neuman , President, UAV IQ
Panel 2: Seeing it in action: Operations that have successfully adopted precision ag tech
- Allison Jordan, Vice President of Environmental Affairs, Wine Institute
- John Erb, Vice President for Sustainable Communities and Resource Solutions, Driscoll's
- Dr. Alvaro Gonzalez, R&D Assistant Manager of the Center for Research & Innovation, Concha Y Toro
Panel 3: Looking ahead: Promising research into the world of precision agriculture
- Dr. Chandra Krintz, Professor, UC Santa Barbara
- Dr. Carlos Flores, Program Coordinator Agronomy and Environment , UC Davis Chile
Register here:
https://register.gotowebinar.com/register/2276456747899022083
- Author: Ben Faber
Pomegranate (Punica granatum) is a specialty crop now grown on more than 10,000 acres in California. Pomegranate production has increased for both fresh market and juice in the last several years, and with this increase, random internally rotted fruit has become more noticed. The outside of the fruit looks perfectly fine, but internally the fruit is rotted and the arils (the flesh covered seeds that are eaten and juiced) are black. Pretty disgusting. Some fruit recently has shown up at harvest and the grower was unaware of the problem until the fruit was opened by a customer. The only difference between good fruit and affected fruit is that the blackhearted fruit is a bit lighter in weight. The absence of external symptoms makes the diagnosis of the disease very difficult, and consumers encountering the disease may change their perception of the pomegranate's many health benefits.
Initially, it was thought that the disease was caused by various fungi that can decay only the arils. However work by Themis Michailides from UC Kearney REC has shown that after inoculation of pomegranate flowers and developing fruit that the main cause of black heart is Alternaria spp. These fungi are very abundant in nature and cause diseases in a multitude of crops. Another fungus that is also isolated from pomegranate with black heart is Aspergillus niger. However, the decay caused by A. niger is softer than that caused by Alternaria and results in exuded juice. In addition, another major difference between black heart caused by Alternaria spp. and that caused by Aspergillus is that the latter decays both arils and rind of fruit and frequently symptoms reach the outer surface of fruit, which helps in the diagnosis of the disease. Inoculations with Alternaria spp. reproduce the typical symptoms of black heart (internal decay of the arils without any external symptoms).
Inoculations periodically with Alternaria spp. showed that most of the infections occur at bloom time and that spores of the fungus that are introduced into the fruit (puncturing from thorns, hemipteran feeding like aphids and stink bugs, or cracking) can result in black heart. The current research focuses on the identification of the various species of Alternaria that cause black heart, the understanding of the infection process, and the development of procedures to manage the disease.
Alternaria alternata and related species commonly occur on plant surfaces and in dying or dead tissues of plants. The pathogens overwinter on plant debris in or on the soil and in mummified fruit. The spores are airborne and can be carried to the flowers with soil dust. Infections may also start from insect and bird punctures on fruit. Research in the San Joaquin Valley showed that the petal fall stage seems to be the most susceptible stage when most of the infection occurs. However, infection can occur throughout the long bloom and fruit development periods.
Estimated losses are usually less than 1% but can be up to 6%.
So how does a grower reduce black heart? Fungicide coverage has been a problem for bloom fungicides, but Michailides has shown some promising new materials. Good orchard management practices, such as dust control and sanitation (removal of old fruit and dead branches), may reduce the incidence of the disease. Infected, healthy-appearing fruit may be dropped to the ground by gently shaking the tree at the time of harvest. Avoid water stress and overwatering that may result in fruit cracking.
Thorough sorting and grading of pomegranates for discoloration and cracking can help avoid packing diseased fruit.
See the Themis' slide show:
- Author: Ben Faber
A fig. A yellow fig. A most delicious 'Kadota' fig. A piece of fruit that falls apart easily and shows every nick, scrape and bump.
And it doesn't take much to reduce a fig to something that is not very attractive to a consumer.
There have been all manner of packing materials that have been devised for shipping fresh figs. Nestled in individual packing hollows they can be shipped to arrive in pretty good condition.
'Bursa Black" which is a 1/4 pound fig grown in the Bursa region of Turkey is shipped to large cities in Europe and because of careful fruit selection and packaging, arrives in excellent shape at the delivery point
Some of these shipping containers pack for individual display, making it easy for the seller to keep from damaging the fruit when removed from the container.
The ultimate shipping container that has been developed for delicate fruit is a "suspended tray" container which floats the fruit to its destination. It's somewhat pricey, so the value of the fruit will determine its value to the shipper. A description of the tray using pears and avocados follows:
SUSPENDED TRAY PACKAGE FOR PROTECTING
SOFT FRUIT FROM MECHANICAL DAMAGE
J. F. Thompson, D. C. Slaughter, M. L. Arpaia
Bartlett pears and Hass avocados are subject to transport vibration damage and their susceptibility to damage
increases as the fruit soften during ripening. Firm fruit,greater than 50 SIQ units (13‐lb penetrometer firmness) for
pears and greater than 65 SIQ units (3.0‐lb penetrometer firmness) for avocados, could be shipped in a wide variety of
conventional packages with little transit vibration damage.However softer fruit sustains significant transit vibration
damage when packed in conventional packaging systems and subjected to severe in‐transit vibration conditions common to cross‐country transit in the United States. This study demonstrated that softer fruit was protected from transit vibration damage when packed in a suspended tray packaging system. The study showed that even eating‐ripefruit could be shipped in the suspended tray system with transit vibration damage not significantly greater than nonvibrated control fruit.
http://ucce.ucdavis.edu/files/datastore/234-908.pdf
But hey, an egg carton may work just about as well.