The pineapple IPM practices are supported by guidelines which were defined by a multi-disciplinary collaboration of faculty from the University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources and Maui Pineapple Company. This program was specifically designed to establish the best management approach for the production of pineapples in the State of Hawaii.
Each practice was individually weighed according to its level of importance to the program. As a method of measurement, a point system is utilized. To receive IPM verification the grower must acquire a total of 80% of the total possible points set forth in the 1999 Elements of Pineapple IPM in Hawaii and provide documentation when records are reviewed. This approach enables growers to maintain flexibility and profitability, while demonstrating its concern for consumers and environmentally sound management practices. Practices and guidelines established for the 1999 pineapple growing season, are subject to change with new IPM developments.
A: SITE PREPARATION
1) Soil test for analysis once per cycle. Maintain records and fertilize according to test results.
Soil testing is critical to any crop fertility program, since it allows identification of nutrient deficiencies which can impair plant growth and also can lead to potential losses of nutrients to the environment. Of most importance in pineapple culture in Hawaii would be testing for pH and available phosphorus. I believe that most other nutrient are apply to the leaves (foliar application) rather than to the soil. However, both lime and P should be applied during soil preparation and deeply tilled in to encourage deep rooting. Although, pineapple does grow well in acid soil, some lime may be required to decrease extreme acidity or to supply Ca as a nutrient.
The consequence of nutrient imbalances can be limited crop growth and therefore reduced uptake of nutrients. If nitrogen uptake is limited by other nutrient deficiencies, the excess N can be leached and become a surface or groundwater contaminant. Also, if excessive P is applied to soil, increased losses of P with soil erosion can cause surface water pollution. Evensen
2) When soil fumigation is preformed, site preparation and application technique maximize efficacy while minimizing rate, volatile losses, ground water contamination, and worker hazard.
Proper site preparation and application are important to maintain efficacy with minimal rates. Field preparation must produce soil which is not clumped or clogged to ensure proper sealing of the chisel trace and seal the plastic mulch in the soil. This will ensure equal diffusion of the fumigant in the bed and prevent loss to the air. ( I think sometimes higher rates are used to compensate for less than adequate technique on the plantations) Proper soil moisture will assist the diffusion of the fumigant in the bed and ensure that the target pest is active and does not escape the effect of treatment.
When Telone II (active ingredient 1,3 -D) is applied at sufficient rates (not to exceed label), it will provide adequate nematode control. Methyl bromide can be used but will be banned soon. 1,3-D is also being developed as an emulsifiable product which will be applied in the drip tube at comparable rates to Telone II. Nonfumigant nematicides are generally much less effective as pre-plant treatments. Sipes
3) Use plastic mulch to optimize efficacy of pre-plant soil fumigant and minimize herbicide use.
Plastic mulch provides an important function for pineapple weed control. Plastic mulch suppresses weeds in the rows of pineapple, which is a very difficult place to apply herbicide sprays without contacting the pineapple foliage. Contact of the foliage with pre-sprays may result in crop injury. Also, the area of the field that is covered with plastic does not need to be treated with pre-emergence herbicide sprays. The use of plastic mulch reduces the area treated with pre-emergence herbicides by 40-50%. DeFrank
1) Use recommended seed fungicide treatment.
It probably would not be economically feasible to grow pineapple in Hawaii (using current growers practices) without fungicide seed treatments to control root rot and heart rot. We know that the fungicide, Aliette, is not very effective at controlling most of the Pythium spp., and we know that the fungicide, Ridomil 2E, is not as effective as Aliette at controlling the Phytophthora spp. However, dipping all seed in both chemicals is prohibitively expensive. Therefore, knowing where the pathogens are causing the most problems will help managers to decide upon which dips to use in which circumstances. This can be best accomplished by regular sampling and analysis of soil and plant tissue samples.
There are three pineapple diseases at Maui Pineapple Co. which can be controlled for a period of time after planting by fungicide seed treatments:
- root rot (caused by Phytophthora cinnamomi, Phytophthora parasitica and several species of Pythium).
- heart rot (caused primarily by Phytopthora parasitica).
- butt rot (caused by Chalara paradoxa).
The following fungicides will provide adequate control of root rot and heart rot (caused by Phytopthora spp) for at least three months after planting: Aliette and Phosphorus acid. Ridomil is not very effective at controlling these Phytopthora diseases, but will provide some control of the Pythium root rots (depending on the Pythium species involved).
The following fungicides will provide acceptable control of butt rot: Bayleton and Elite. Also, cured crowns are more resistant to attack by Chalara paradoxa than non-cured crowns. Nelson
2) Minimize compaction to minimize root rot & optimize root growth.
Growing pineapple in compacted soil reduces root mass and health. A large, healthy root system is more able to tolerate disease than a small, stunted root system. Compacted soil holds water longer than soils with better structure. Thus, compacted soil provides conditions suitable for the development of root rot and heart rot. Nelson
C. PEST MONITORING AND MANAGEMENT
1) Mealybug Wilt Management
1A) Monitor ants on a regular basis and apply ant bait as needed.
Mealybugs in the genus Dysmicoccus (Homoptera: Pseudococcidae) infest commercial pineapple plantings worldwide, impacting pineapple production in several ways (Beardsley 1993). They may infest developing plants and fruit, thereby functioning as direct pests to the crop, reducing fruit quality and quantity by impacting plant development (Carter 1933), and producing honeydew that serves as a source for growth of sooty mold, Capnodium sp. Feeding of Dysmicoccus species on pineapple produces a toxic effect called mealybug stripe, expressed as green or black striped areas (Carter 1967). Growth depression may result from mealybug feeding, and is best expressed in small pineapple seedlings (Carter 1962). Their direct impact on fruit production has not been quantified. Sometimes mealybugs are found as contaminants in canned fruit, and their presence on fresh market fruit may violate quarantine restrictions at port entrances. The mealybugs' greatest impact is associated with the disease mealybug wilt of pineapple (MW) (Rohrbach et al. 1988). This association makes Dysmicoccus mealybugs the most economically significant pineapple pest in Hawaii (Rohrbach et al. 1988). Although this disease is reported worldwide and has posed a significant threat to the pineapple industry for more than 80 years, the etiology of this disorder remains unclear (Rohrbach et al. 1988, German et al. 1992).
Mealybug wilt appears to occur when Dysmicoccus feeding stresses pineapple plants (Rohrbach et al. 1988). In Hawaii, the mealybugs associated with this problem are the pink pineapple mealybug, Dysmicoccusbrevipes (Cockerell), and the gray pineapple mealybug, Dysmicoccusneobrevipes Beardsley (Beardsley 1993), the former species being most common (Gonzalez-Hernandez 1995). Carter (1933) categorized MW into "quick wilt" and "slow wilt," with the former disorder resulting from a sudden mealybug infestation allowed to feed for a short time in contrast to the latter disorder which results from sustained feeding of high mealybug densities over a long period. Recovery from both types of wilt is possible if remedial actions are implemented prior to substantial plant injury. The most obvious MW symptom is drying and wilting of the foliage, beginning at the leaf tips (Singh & Sastry 1974). Foliage later turns reddish-yellow in color. If uncontrolled, the plant's roots collapse, resulting in plant death (Carter 1948). Without sufficient mealybug control, whole plantings may be lost due to mealybug wilt, resulting in lost fruit production.
In 1989, a pineapple closterovirus (PCV) was purified and partially characterized from diseased pineapple tissue in Hawaii by Gunasinghe & German (1989) and Ullman et al. (1989), giving validity to the hypothesis of a viral etiology for MW. Since then, closterovirus-like viruses have also been purified from diseased pineapple in other countries such as Australia (Wakman et al. 1995). Given the previous inability to identify PVC in pineapple plants, no definitive studies have been completed on the relationship between mealybug-induced stress and the production of MW in PCV infected plants. Likewise, it is not known what impact mealybug densities have on PCV-free plants. This knowledge is necessary for the development of economic thresholds that allow one to initiate mealybug controls prior to significant losses due to mealybug infestations. Currently, pineapple plantings must be maintained practically mealybug-free because it is not known what constitutes an economically significant mealybug density relative to PCV-infected and PCV-free plants. Growers utilize a "preventative" application strategy to keep plants mealybug free. Thus, pineapple plantings are not monitored for mealybug infestations and no simple grower-usable sampling programs (e.g., binomial sampling) exist. Knowledge relative to the importance of various mealybug densities as well how to easily monitor mealybug densities would not only allow one to make more informed decisions relative to the need for implementing mealybug controls, but would also reduce pesticide use and define the levels of biological control necessary to maintain healthy pineapple plantings.
MW control via mealy bug and ant management.
Recent work by Gonzalez-Hernandez (1995) showed that the parasitoid Anagyrus ananatis Gahan (Hymenoptera: Encyrtidae) can maintain populations of the pink pineapple mealybug at levels that do not induce mealybug wilt in pineapple. Unfortunately, ants such as big-headed ant, Pheidole megacephala (L.), (Hymenoptera: Formicidae) inhabit pineapple plantings and protect the pineapple mealybugs from A. ananatis and other natural enemies. Ants benefit from this association because they obtain honeydew from the mealybugs. Currently, pineapple growers apply the hydramethylnon-bait insecticide AmdroŽ (American Cynamid Co., Wayne, NJ) that provides excellent ant control and thereby allows A. ananatis and other natural enemies to control the mealybugs. This strategy depends on the continued annual approval of the Environmental Protection Agency and the Hawaii Department of Agriculture which permit this product to be used on a special needs basis. At present, registration for AmdroŽ under section three is pending. The approval of this product is anticipated by the year 2000. Johnson
Control of MWP via virus management. The pineapple closterovirus (PCV) has been shown to be transmitted by mealybugs from diseased pineapple plants to healthy pineapple plants. Recently, our results also demonstrated that PCV and mealybug feeding alone did not induce MWP symptom development, and that the interaction of PCV and mealybug feeding induced typical MWP symptoms. Therefore, it is possible to develop alternative methods to control MWP via virus management. Currently, the virology group at UH is working on determination of the impact of PCV in MWP and pineapple production, identification of the spectrum of the pineapple closteroviruses which are associated with MWP, study of the population diversity and insect transmission of the viruses, and development of alternative methods to manage mealybug wilt. These alternative methods include utilization of PCV-free pineapple plants as planting materials and development of transgenic pineapple plants which are resistance to pineapple mealybug wilt closteroviruses. Both of the methods are environmentally-sound and will help to reduce or eliminate the use of environmentally harmful chemicals so that to reduce the risks to human health and environment. In the future, these alternative control methods will be integrated into the pineapple IPM program for the control of MWP. Hu
2) Nematode Management
2A) Determine plant-parasitic nematode control strategy using field history and (knockdown/current) nematode population densities.
Nematode populations must be assayed at predetermined intervals ( such as 3 , 5, 7, 9 months) after planting. When the nematode population is above 100/250 cm3, a post plant nematicide should be used. Historical field data is used to determine pre-plant nematicide treatments. Acceptable nematicides are fenamiphos and ethoprop. New products are being evaluated and may provide additional alternatives within a few years. Sipes
2B) Monitor nematodes on a regular basis during plant crop vegetative growth cycle.
Nematode populations must be assayed at predetermined intervals (such as 3 , 5, 7, 9 months) after planting. Sipes
3) Root Rot Management
3a) Use raised bed/ridge to reduce root rot in sensitive areas.
The biological rationale for this practice is as follows:
a) Pathogen ecology. Some root rot pathogens (e.g., Phytophthora parasitica and several Pythium spp.) produce zoospores as principal infectious propagules. These zoospores are equipped with flagella (small, whip like structures used for propulsion through water) that assist the spores in swimming through the moisture-laden soil profile. Zoospores are produced and released under wet conditions. Thus, infection occurs under wet conditions. The combined processes of zoospore production, release and infection can occur in less than 24 hours. Therefore, by reducing the amount of time that soil remains saturated or flooded, the amount of spores produced is reduced, as is their capability to be released and infect pineapple roots. We know there is a direct relationship between soil matric potential (amount of water held by the soil) and disease severity. When matric potential approaches 0 bars (flooded conditions), disease severity is greatest. When soil matric potential increases (soil becomes less wet), disease intensity diminishes. By planting on raised beds, the amount of time that soil matric potential is in the danger zone is reduced significantly. These pathogens are known as the water molds.
For heart rot, planting on raised beds will also minimize the probability that pathogen spores will be splashed from soil surface into heart of pineapple plant.
b) Host ecology: If roots are water-logged, they become more susceptible to infection and disease development. Leachates from roots under these conditions can attract the zoospores of the pathogens. Roots become softer and less able to resist infection.
Potential problem of raised beds: increased water requirements during dry season (increased costs)
Recommended height of beds: 8-12 inches minimum. Nelson
4) Weed Management
4A) Apply pre-emergence herbicide in critical areas and before canopy closure.
Pre-emergence herbicides should be applied after planting to the between row space on a field by field basis. Pre-emergence herbicides should be applied based on field scouting reports to match rates of application to the most difficult to control weeds. Pre-emergence herbicide rates can be reduced by forcing weeds to grow after the in row plastic mulch is installed but before planting pineapple. Many difficult to control weeds such as morning glory can be germinated with sufficient amounts of irrigation and then killed with a contact herbicide. Pre-emergence herbicides applied after weeds are killed will be more effective due to less weed seeds being present. Herbicide rates may be significantly reduced if current use patterns are based on the control of weeds that could be easily removed by this pre-plant treatment.
Additional spot treatments with pre-emergence applications should be made to any open areas remaining after the majority of the field has achieved a closed canopy.
After the final crop harvest, prevention of seed formation from weed escapes is very important in reducing herbicide use in subsequent crops. Weeds should be killed with contact herbicides before the field is plowed or disked. Intact weeds will be more completely killed than weeds with disturbed roots caused by a disc harrow or similar tool. The plantation should consider chopping or mowing the standing pineapple to provide a surface mulch for long-term weed suppression during fallow periods. Mulched fields would also retain more moisture for subsequent crops, allow more rainfall infiltration, reduce runoff and help to mitigate fugitive dust.
Pre-emergence herbicides should not be applied to fallow fields unless there is assurance of activation with either rainfall or overhead irrigation. Pre-emergence herbicides applied and not activated with 2-3 weeks will be reduced in effectiveness via photo decomposition or volatilization. Pre-emergence herbicides applied to fallow fields can be easily lost to wind or water erosion. Soil particles laden with pesticide residue can represent a non-point source of pollution. Spot applications of weeds with contact herbicides would be preferred to blanket pre-emergence application in fallow fields. DeFrank
4B) Monitor and establish weed maps to determine which weeds are dominant in specific sites.
Fields should be scouted to determine which weeds are dominant in specific sites. Individual weed species should be categorized with respect to sensitivity to registered pre-emergence herbicides. Herbicide rates should be adjusted for each field and based on weed populations present so that the minimum amount of herbicide is used at each location. DeFrank
4C) Use of cover crops to minimize weeds that could be host to pineapple pest, or to depress nematode population, or to increase nitrogen levels.
Cover crops are used for the suppression of weeds (Cohesion and Boerner 1991) and soil borne diseases during fallow periods. Brassica cover crops are used for nematode (Mojtahdei et al 1991) and disease (Johnson et al 1992) suppression. Furthermore, Sudan grass cultivars are used as cover crops for the suppression of nematodes during the fallow period (Mojtahedi et al 1993). DeFrank
5) Sprayer Calibration
5A) Calibrate sprayers accurately annually.
Sprayer calibration is important for several reasons: 1) to obtain the performance of a pesticide as specified on the product label, 2) to be able to repeat successful procedures and minimize expenses, 3) to diagnose problems with failure in product performance or crop injury, 4) to be able to document legal doses applied when using Restricted Use Pesticides.
For the accurate application of pesticides, certain considerations should be taken into account. This would include such things as: 1) volume required to cover a known surface area with a specific type of spray equipment, 2) amount of pesticides recommended on an area basis, 3) formulation or concentration of the commercial pesticide formulation, 4) size of the tank from which the pesticide is being delivered, and 5) ability to maintain consistent spray pressure, ground speed and proper nozzle height for recommended overlap. DeFrank
D. POST HARVEST
1) Crop residue turned under and incorporated after last harvest.
Destruction of the existing pineapple root system will stop nematode reproduction and begin reducing nematode population densities. Delay in crop destruction allows the nematode population to continue increasing. Sipes
When residue is disked under, it reduces the probability that pathogen spores will be carried by splashing or running water (or by wind) to neighboring fields. Disking under enhances the probability that beneficial soilborne organisms will compete with the pathogens in the soil profile. Nelson
Turning under pineapple crop residue disposes of the massive amount of material without the air pollution caused by burning. In addition to reducing pathogens harbored in the residue, soil organic matter is increased, which results in better nutrient holding capacity of the soil. Also, the increased soil organic matter results in improved soil structure, better soil aeration, increased permeability and increased moisture holding capacity. The main constraint is the long fallow period (at least 6 months or longer) which is require for this high fiber residue to break down and the potential for N immobilization during decomposition due to the high C:N ratio or the residue. This is already a common practice in the pineapple industry in Hawaii and soil improvement has been noted to accompany incorporation of residue.
The incorporation of residue and resulting increases in soil permeability and moisture holding capacity would help to reduce erosion from pineapple fields.
As noted above, the incorporation of crop residue is very beneficial in improving soil fertility and moisture holding capacity. Disking the residue under soon after the last harvest would allow the decomposition to take place more quickly and would reduce the potential spread of pests and diseases in the residue. So long as the disking or tillage leaves a fairly rough field surface, the erosion hazard of the field should generally be low since the depressions and deep furrows created and the increased soil permeability will allow most rainfall to be retained and absorbed into the soil. Evensen
2) Maintain a fallow period of at least 3 months between crop cycles.
Non host (sweet corn, rape seed, sunn hemp, marigold, wheat, rye) or bare fallows reduce nematode population levels. Over time, sufficient fallowing can eliminate the need for pre-plant fumigation. Sipes
FUTURE AREAS OF RESEARCH
Monitor Scavenger moth and apply insecticide when needed.
The pink scavenger moth (Pyroderces rileyi ) is a seasonal pest which lessens the quality of fruit. At night, the adult moth lays its eggs at the base of the fruit. The biology and ecology of the pest is not fully understood.
Pink Disease Bacteria
Pink Disease Bacteria presently is a sporadic problem, which is managed by proper field sanitation. Weed management is an essential component in the prevention and management of this disease.
University of Hawaii Multi Disciplinary CommitteeDeFrank, Joseph Horticulture/ Weed Science Evensen, Carl Agronomy and Soil Science Hu, John Plant Pathology Johnson, Marshall Entomology Kawate, Michael Environmental Biochemistry Mau, Ronald Entomology Nelson, Scot Plant Pathology Sipes, Brent Plant Pathology
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