9 Pests, Diseases and Weeds
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Pineapple Chapter 09 14/10/02 2:13 PM Page 203 9 Pests, Diseases and Weeds Kenneth G. Rohrbach and Marshall W. Johnson Plant and Environmental Protection Sciences, CTAHR, University of Hawaii at Manoa, 3190 Maile Way, Honolulu, HI 96822, USA Introduction drained soils. The adventitious roots arising from the lower portion of the pineapple stem Several recent in-depth reviews of pineapple are the only ones that become soil roots. Once pests and diseases have been published the root system is damaged or destroyed, it (Lim, 1985; Rohrbach and Apt, 1986; does not regenerate significantly. Broadley et al. 1993; Rohrbach and Schmitt, Indices for pineapple-plant diseases are 1994). The focus of this chapter is on the the proportion of the plant population interactions of populations of pineapple affected (incidence) and the effect of disease pests, disease pathogens and weeds with the on each plant (severity). Severity may range pineapple production cycle. High population from a reduction in growth rate, as indicated densities of pineapple pests, diseases and by a reduced plant size or weight, to a weeds occur at different times in the pine- reduced fruit yield. Pineapple pest indices apple life cycle (shown by varying bar inten- applicable to IPM systems have been devel- sity for each insect and disease pathogen in oped for mealybugs, ants and mites. Figs 9.1, 9.2 and 9.3), and therefore have In order to understand the epidemiology varying impacts. Understanding the inter- of pineapple-plant diseases and to develop actions of these pests and disease pathogens management strategies, the probability of with their pineapple host is critical to an disease occurrence (frequency) and the level integrated pest, disease and weed manage- of disease occurring (incidence and severity) ment (IPM) programme. must be considered. Indices for fruit disease Several characteristics of the pineapple severity are shown in Figs 9.4 and 9.5. Factors plant and commercial pineapple production of importance are the presence or absence of systems contribute to the severity of several the causal organism, susceptibility of culti- pest and disease problems. The commercial- vars and optimum environmental conditions. ization of pineapple required large capital investments in land and processing facilities, Fallow Period (Intercycle) which has resulted in long-term monoculture. Long-term monoculture has contributed to Intercycle pests severe nematode problems in many produc- tion areas and this has required the imple- Nematodes, mealybugs and ants mentation of nematode-control strategies. The pineapple plant is most productive In a monoculture pineapple production under a xerophytic environment where low system, the fallow period or intercycle has rainfall is supplemented by irrigation in well- historically ranged from years to as little as a © CAB International 2003. The Pineapple: Botany, Production and Uses (eds D.P. Bartholomew, R.E. Paull and K.G. Rohrbach) 203 Pineapple Chapter 09 24/10/02 11:30 AM Page 204 204 K.G. Rohrbach and M.W. Johnson Seed Planting Growth Forcing Flowering Harvest Mealybugs Ants Bud moths Scale Thrips Fruit mite Red mite Symphylids White grubs Fig. 9.1. Illustration showing typical frequencies of infestation of the most significant pineapple pests in relation to a plant-crop pineapple cycle. Darker area indicates higher frequencies. Seed Planting Growth Forcing Flowering Harvest Mealybug wilt Nematodes Butt rot Heart rot Root rot Yellow spot Fusarium stem rot Bacterial heart rot Fig. 9.2. Illustration showing typical disease intensities of the most significant pineapple diseases in relation to a plant-crop pineapple cycle. Darker areas indicate higher intensities. few weeks. Prior to the discovery of soil the control of ants and mealybugs which are fumigants for nematode control, the fallow associated with mealybug wilt. Tillage must period was an important nematode-control be thorough and frequent enough for the strategy, particularly for the root-knot nema- decomposition of the previous crop and its tode. The fallow period is also important for pests and for the elimination of weed growth Pineapple Chapter 09 14/10/02 2:13 PM Page 205 Pests, Diseases and Weeds 205 Seed Planting Growth Forcing Flowering Harvest Consumer Black rot Penicillium/Fusarium fruitlet core rot Fusariosis Pink disease Fruit collapse Marbling disease Internal browning Fig. 9.3. Illustration showing typical pineapple fruit disease intensities of the most significant pineapple fruit diseases in relation to a plant-crop pineapple cycle. Darker areas indicate higher intensities. 1 = 1–2% 2 = 3–5% 3 = 6–10% 4 = 11–25% 5 = 26–50% 6 = 51–100% Fig. 9.4. Pineapple disease index used to measure external disease severity (e.g. black rot) based on the proportion of fruitlets per fruit that show symptoms. during the fallow period. Weeds present dur- Ants present in intercycle fields are the ing the fallow period may provide a carry- big-headed ant, Pheidole megacephala (F.) over host for nematodes and mealybugs. (Plate 22), the Argentine ant, Iridomyrmex Thorough tillage can also eliminate ants humilis (Mayer), and the fire ant, Solenopsis within the fallowed field. geminata (F.) (Rohrbach and Schmitt, 1994). Pineapple Chapter 09 14/10/02 2:13 PM Page 206 206 K.G. Rohrbach and M.W. Johnson 1 = 1–2% 2 = 3–5% 3 = 6–10% 4 = 11–25% 5 = 26–50% 6 = 51–100% Fig. 9.5. Pineapple disease index used to measure internal disease severity (e.g. internal browning) based on the proportion of fruitlets per fruit that show symptoms. With deep, frequent intercycle tillage, most Several different species may infest trash or ant colonies can be eliminated. overripe pineapple fruit, of which Carpophilus Nematode populations during the fallow humeralis (F.), Carpophilus hemipterus (L.) (Fig. period will decline significantly if soil mois- 9.6), and Haptoncus ocularis (Fairm) are the ture is adequate. However, the presence of most common (Carter, 1967; Py et al., 1987). soil moisture increases the need for weed Fertile females may lay more than 1400 eggs control. Dry fallow is not as effective at and live as many as 115 days (Carter, 1967). reducing the reniform nematode population Eggs usually hatch within 2 days after depo- as is wet fallow (Caswell and Apt, 1989). sition. Hinton (1945) indicates that the life Economic thresholds for nematodes are cycle of C. humeralis from egg to adult is not well defined. Soil sampling is important about 21 days. While the larvae typically because the qualitative occurrence of reni- feed on decaying fruit, the adults may attack form, root-knot or root-lesion nematodes is pineapple plants at every stage of growth generally interpreted as a potential problem (Hinton, 1945). They may congregate on seed that requires control (Caswell et al., 1990; plants placed in the field and feed on the Stirling and Kopittke, 2000). exposed butts and starchy stalk material. However, the injury to the plant is not eco- nomically significant. Chang and Jensen Souring beetles (1974) have identified these beetles as being Small nitidulid beetles (c. 4.5–8.0 mm), possible vectors of the fungus Chalara para- known as souring beetles, sap beetles or doxa (De Seynes) Sacc. (syn. Thielaviopsis dried-fruit beetles, are attracted to decom- paradoxa (De Seyn.) Hohn) (telemorph posing pineapple plant material (termed Ceratocystis paradoxa (Dade) C. Moreau) pineapple trash) following knock-down of which causes black-rot disease. the previous crop. The adult beetles are Souring beetles are more of a social nui- hard-bodied and dark brown (Hinton, 1945). sance than an agricultural one, because they Pineapple Chapter 09 14/10/02 2:13 PM Page 207 Pests, Diseases and Weeds 207 Fig. 9.6. Souring beetle, Carpophilus hemipterus L. often land on humans in the vicinity of Intercycle cover crops knocked-down fields and fruiting pineapple plantings. This has been a problem in places While intercycle cover crops have not been such as Hawaii, where recreational and utilized to any degree in commercial pine- tourist activities (e.g. golf) are enjoyed near apple production, they offer some potential pineapple-production areas. It has been for controlling erosion and reducing nema- reported (R. Heu, personal communication) todes (Ko and Schmitt, 1993). Their use has that a single Maui resort company lost been uneconomic because adequate rainfall $50,000 weekly due to problems stemming or irrigation is necessary to sustain cover from swarms of adult souring beetles. Given crops in dry production areas. that these beetles do not have a significant impact on pineapple production, it is not economically feasible or environmentally Seed Material – Collection, Handling and desirable to control them with pesticides. Storage However, to reduce their nuisance factor, the parasitic wasp Cerchysiella (= Zeteticontus) Pineapple is vegetatively propagated, utiliz- utilis Noyes (Hymenoptera: Encyrtidae) was ing crowns, slips or suckers (Fig. 9.7). In gen- collected in Israel and released in Hawaii in eral, these ‘seed materials’ are infested with 1977 to control the immature larval stages of the same pests as were present on the the beetles that infest rotting pineapple trash mother plants. The movement of seed mate- and fruit (Funasaki et al., 1988). The wasp rials from field to field or country to country established populations on the Hawaiian has been the primary means of spread of the Islands of Oahu, Maui and Lanai (C. major pineapple pests and diseases Nagamine, personal communication). The (Rohrbach, 1983). Common pests infesting adult female parasitoid deposits her eggs seed materials are mealybugs, scale and into beetle larvae and the parasitized larvae pineapple red mites. In addition to these mummify (i.e. turn hard and stiff) after 9–11 pests, the diseases termed butt rot and days. Fifteen days after egg deposition, an Fusarium stem rot may be major problems adult C. utilis emerges from the parasitized when handling, storing or planting fresh beetle.