Alternative species to replace Monterey pine plantations affected by pitch canker caused by Fusarium circinatum in northern Spain

The pitch canker pathogen Fusarium circinatum was first found to cause damage in nurseries and pine plantations in northern Spain in 2004. Since then, establishment of pine plantations in the region has decreased as a result of the prohibitions placed on planting Pinus spp. and Pseudotsuga menziesii in areas affected by the disease. However, although most pine species have been found to be susceptible to the pathogen under nursery conditions, little is known about how the fungus affects the trees in the field. Furthermore, it is not known whether some of the native or exotic species commonly planted in the area are also susceptible to F. circinatum. The aim of this study was to evaluate the susceptibility of several conifer species commonly planted in northern Spain to the pitch canker pathogen. For this purpose, two different trials were carried out, one under controlled laboratory conditions and the other in the field. Although most of the conifers were affected by the pathogen in the laboratory tests, only Pinus radiata, Pinus nigra, Pinus pinaster and Pinus uncinata were susceptible to the pathogen in the field.     

A Comparison of DDT w.p. and Dieldrin e.c. for Tesetse Fly Control in Botswana

Abstract

During the present century increasing world demand for forest products has brought about a rapid expansion of even-aged forest plantation estates, requiring the forester to adopt the outlook and techniques of the farmer to an increasing extent, both to maintain yield and protect crops from damage.

Aircraft have already proved their worth in the protection of natural and artificial forests from fire and are frequently used for seeding, fertiliser application, survey and the control of insect pests. They are also potentially useful for the control of forest diseases, although their role in this respect has so far been limited. The development of aerial spraying to control dothistroma blight of Pinus radiata is reviewed in this paper.     

Effect of Trichoderma viride pre-inoculation in pine species with different levels of susceptibility to Fusarium circinatum: physiological and hormonal responses

Pine pitch canker (PPC), caused by Fusarium circinatum, affects Pinus species worldwide. Although no effective solutions have yet been found to control it, there is a growing interest in using biological control agents (BCA) such as Trichoderma to avoid the application of chemical-based products. Using species with an increasing level of susceptibility to PPC (Pinus pinea, Pinus pinaster and Pinus radiata), this study aimed to evaluate the effect of Trichoderma viride pre-inoculation on disease development, assessing several physiological and hormonal parameters. A 2-week period elapsed between T. viride and F. circinatum inoculation. Sampling for each species was performed independently when at least 50% of the plants of one of the inoculated groups developed disease symptoms. Fusarium circinatum infection reduced water status and photosynthesis, but increased proline, abscisic acid and jasmonic acid concentrations in plants of P. radiata and P. pinaster with symptoms; while in P. pinea water relations were maintained and anthocyanin accumulation occurred in the presence of F. circinatum. In P. radiata, T. viride pre-inoculation accelerated disease progression, with some PPC-induced responses augmented (decreased water potential and photosynthesis; increased substomatal CO₂ concentration) and novel changes not found in seedlings inoculated exclusively with F. circinatum (increased electrolyte leakage and salicylic acid; decreased relative water content). This suggests that T. viride may be initially recognized as an invading organism, subverting the plant defence mechanisms for successful root colonization. If seedlings are not allowed to recover from this state, pathogen infection may thus be facilitated, highlighting the importance of application timing in BCA strategies.     

New distribution records ofMatsucoccus josephi andPineus pini (Homoptera) on pine trees in parts of the near east

Information is presented on new occurrences of two homopteran pests,Matsucoccus josephi Bodenheimer et Harpaz (Matsucoccidae) andPineus pini (Macquart) (Adelgidae), in Israel, Jordan and southern Lebanon.M. josephi occurs in Israel in almost all natural relicts of Aleppo pine (Pinus halepensis). It infests all plantations of Aleppo pine, brutia pine (Pinus brutia ssp.brutia) and Eldar pine (P. brutia ssp.eldarica) north of 31°12′ lat. N. Heavy damage has been observed in the Judean Foothills, Judean Mts. and northern Samaria.M. josephi and its specific predator,Elatophilus hebraicus Pericart (Hemiptera: Anthocoridae), are recorded for the first time in Jordan and southern Lebanon. The scale was found in all visited Aleppo pine and brutia pine stands in Jordan and in natural and planted brutia pine in southeastern Lebanon. Damage byM. josephi in Jordan was observed only in young plantations of Aleppo pine; in Lebanon no signs of injury were recorded.P. pini was found for the first time in Jordan, where it causes severe damage to young stands of Aleppo pine and stone pine (Pinus pinea). Contribution from the Agricultural Research Organization. No. 1225-E, 1993 series.     

The Role of the Bark Beetle, Hylastes ater (Coleoptera: Scolytidae), as a Sapstain Fungi Vector to Pinus radiata Seedlings: A Crisis for the New Zealand Forestry Industry?

The role of the bark beetle Hylastes ater in the re-establishment of Pinus radiata forest in New Zealand is discussed. H. ater was found to be a dominant factor in seedlings mortality in the first year following planting. However, seedling mortality is usually relatively low. In contrast, it was found the large numbers of seedlings were sub-lethally damaged by H. ater feeding attempts, particularly in high risk sites. High risk sites were identified as sites that were harvested during March and April (autumn) when the peak flight activity of H. ater occurred, and subsequently planted with P. radiata seedlings the following winter. H. ater was found to vector sapstain fungi to seedlings during feeding attempts, and a strong relationship between the severity of damage and presence of sapstain fungi was identified. The role of H. ater as a vector of these fungi and the potential implications to the New Zealand forest industry are discussed.     

Different breeding systems of three varieties of Bidens pilosa in Taiwan

Three varieties of the introduced Bidens pilosa (Hairy beggar‐ticks; Asteraceae) co‐exist in Taiwan. Bidens pilosa var. minor and var. pilosa are naturalised, while only var. radiata is invasive. Differences in seed set in bagged versus open‐pollinated capitula, pollen–pistil interactions and the pollen/ovule (P/O) ratio were investigated among these three varieties. In contrast with the resulting 45–55% seed set in each bagged capitulum of var. minor and var. pilosa, almost no mature seeds (1–2 seeds) were found in bagged capitula of var. radiata, showing that var. radiata has a low capability of autonomous seed production. In bagged capitula, only 1.5% of pistils of var. radiata, but 76% and 52% of those of var. minor and pilosa, respectively, had pollen tubes penetrating into their styles, suggesting that var. radiata has strong self‐incompatibility mechanisms preventing autonomous autogamy. The P/O ratio, with mean values of 8189, 2053 and 1613 for var. radiata, var. minor and var. pilosa, respectively, were counted. These results support the hypothesis that the three varieties bear different breeding systems; the invasive var. radiata is highly self‐incompatible, whereas the other two naturalised varieties are self‐compatible.     

Alternatives to hexazinone and terbuthylazine for chemical control of Cytisus scoparius in Pinus radiata plantations in New Zealand

Two herbicides used for post‐plant weed control in commercial forests in New Zealand, terbuthylazine and hexazinone, are not endorsed for use on land certified by the Forest Stewardship Council (FSC). These herbicides are effective for controlling competitive woody weeds, such as Cytisus scoparius (broom). To investigate the potential of non‐residual, alternative herbicides for the control of C. scoparius after planting, a range of treatments were implemented at two trials. The trials were established in newly planted Pinus radiata plantations where C. scoparius dominated. The objectives were to (i) optimise application rates of alternative herbicides and compare their efficacy to current practice and (ii) identify if treatment efficacy varied across sites. Treatments at each site included weedy and weed‐free controls, current practice using terbuthylazine and hexazinone, applied as both spot treatment and broadcast application, and a range of new treatments consisting of different dosage combinations of clopyralid, triclopyr and picloram. Broadcast application of the clopyralid, triclopyr and picloram mixture showed increasing weed‐control efficacy against C. scoparius with increasing dose rate, resulting in increased tree volume. Broadcast application of the clopyralid, triclopyr and picloram mixture at 75% or 100% of a typical industry use rate (100% industry rate includes clopyralid 1.5 kg a.i. ha^?1, triclopyr 0.15 kg a.i. ha^?1 and picloram 0.05 kg a.i. ha^?1) achieved greatest tree volume by year four with tree volumes exceeding that obtained using the operational spot treatment with terbuthylazine and hexazinone. Treatment rankings were similar between locations. The result supports the use of clopyralid, triclopyr and picloram to control C. scoparius during the first year of P. radiata establishment.     

Occurrence, isolation and biological activity of phytotoxic metabolites produced in vitro by Sphaeropsis sapinea, pathogenic fungus of Pinus radiata

Sphaeropsis sapinea was repeatedly isolated in Sardinia from symptomatic samples of the upper part of declining pine (Pinus radiata) plants. Observed symptoms mainly consisted of foliage chlorosis, drying of needles and cankers on branches. The S. sapinea strains were shown to produce phytotoxic metabolites in culture filtrates. Three metabolites were isolated for the first time from this fungus and identified by their spectroscopic and optical properties as R-(−)-mellein, (3R,4R)-4-hydroxymellein and (3R,4S)-4-hydroxymellein. When assayed for phytotoxic and antifungal activities on host and non-host plants and on some phytopathogenic fungi, the R-(−)-mellein showed significant activity, while the other two 3,4-dihydroisocoumarins showed only a synergic activity in both tests.     

Evidence for a new introduction of the pitch canker fungus Fusarium circinatum in South Africa

Fusarium circinatum causes pitch canker of Pinus species in many parts of the world. The fungus was first recorded in South Africa in 1990 as a pathogen of P. patula seedlings and emerged later as a pathogen of established plantation trees, especially P. radiata in the Western Cape Province (WCP). In this study the population biology of F. circinatum in the WCP was explored. The aim was to determine the possible origin and reproductive mode of the pathogen, with the ultimate intention of informing disease management strategies in the region. Vegetative compatibility assays, sexual mating studies and amplified fragment length polymorphism analyses were used. For comparative purposes, an isolate collection obtained from diseased P. radiata seedlings in a commercial nursery in the region, as well as a set of isolates from commercial seedling nurseries in the central and northern parts of South Africa, were included. The results showed that the WCP population of F. circinatum employs a predominantly asexual mode of reproduction and that it is highly differentiated from populations of the fungus elsewhere in South Africa. However, limited genetic structure was found within the respective WCP isolate collections. Overall these findings suggest that pitch canker in the WCP originates from one or more separate introductions of the pathogen and that its movement in the region is not restricted. More effective strategies are thus required to limit and manage the effects of F. circinatum in plantations in this region of South Africa.     

Epidemiological studies on powdery mildew of mungbean and urdbean

Abstract

Powdery mildew of mungbean (Vigna radiata L. Wilczek) and urdbean ( V. mungo L. Hepper) caused by Erysiphe polyponi DC during the winter/spring season is a severe constraint in the production of bean crops in the Chhattisgarh region of Madhya Pradesh. Keeping this in view, studies were made to understand the development of powdery mildew in relation to crops, varieties, weather conditions and their effect on yield. The first appearance of powdery mildew in 33 mungbean and 18 urdbean varieties was 1 week earlier during winter 1992–93 than winter 1991–92. Its development was most rapid each year when the average maximum temperature varied from 27.2 to 30.3°C, relative humidity from 67 to 90% during the morning and 12 to 38% at noon, and wind velocity from 2.3 to 4.1 km/h. A positive correlation occurred between mildew severity and temperatures and wind velocity in most of the varieties. However, the correlation with relative humidity was negative and significant except in a few varieties. The pooled infection rates (r)/unit/day on resistant mungbean and urdbean varieties was less than 0.1 with disease scores of 1–5 while in apparently slow mildewing varieties, rvalues were also less than 0.1 but showed a score of 7–9. The effect of disease levels on grain yield of urdbean had a negative and significant correlation. However, it was negative but not significant in the case of mungbean. Grain yield was considerably higher when the crops were protected with one spray of Bavistin (1 kg/ha in 5001 of water) followed by Sulfex (3 kg/ha in 5001 of water) than in the untreated control. The disease scores in sprayed plots were also markedly less and ranged between 0 and 5 as against 1 and 9 in the untreated control in different varieties.     

Problem of flower shedding caused by thrips,Megalurothrips distalis (Karny), on summer mungbean,Vigna radiata (L.) Wilczek,and its control

Abstract

Flower shedding in summer mungbean, Vigna radiata (L.) Wilczek, is a common feature caused by thrips, Megalurothrips distalis (Karny). Eleven insecticides were tested in field trials for the control of thrips during the period 1982 to 1984. All the treatments were significantly better in controlling the thrips, reducing flower shedding, increasing the pod numbers and grain yield, in comparison with the control. Increases in yield compared with the control during trials ranged from 85 to 89% (1982), 26 to 96% (1983) and 5 to 194% (1984). Dimethoate gave the highest increases in yield and profit followed by monocrotophos and endosulfan.     

亮腹釉小蜂成虫触角感受器的超微结构

为进一步了解柑橘木虱Diaphorina citri若虫的优势寄生蜂亮腹釉小蜂Tamarixia radiata的寄生行为,利用扫描电镜对亮腹釉小蜂雌雄成虫触角感受器的种类、分布和形态进行观察。结果表明,亮腹釉小蜂雌成虫触角上存在5种感受器,分别是刺形感受器、毛形感受器、乳头状感受器、板形感受器和末端指形感受器;亮腹釉小蜂雄成虫触角上存在4种感受器,分别为刺形感受器、毛形感受器、乳头状感受器和板形感受器;其中毛形感受器又可以根据外部形态的差异划分为4个亚型,即毛形感受器类型1、2、3、4。此外,板形感受器、毛形感受器类型2和毛形感受器类型3在亮腹釉小蜂雌成虫触角上的分布数量显著多于雄成虫触角上的分布数量。这些形态学差异有助于深入理解不同性别亮腹釉小蜂的触角感知行为。     

Differences in constitutive and inducible defences in pine species determining susceptibility to pinewood nematode

The pinewood nematode, Bursaphelenchus xylophilus, originating from North America (NA), is a major invasive pine pest in Eurasia. It was first detected in Portugal in 1999 associated with maritime pine, Pinus pinaster, and has been differently affecting the main local pine species, P. pinaster and P. pinea. Field studies and direct inoculation experiments in Pinus spp. seedlings, under controlled conditions, were performed to assess whether the differences in constitutive and inducible defences are determining the different susceptibility of pine host species to B. xylophilus. Host co‐evolution with the pathogen was also assessed, including the NA P. radiata, widely used in forestry in the northeast of the Iberian peninsula. Pine mortality in the field was positively related with the abundance of B. xylophilus, and concentration of phenolics and condensed tannins in pines. In the greenhouse assay, seedling tissues were analysed for constitutive investment in defences, as well as the potential inducibility of those defences as driven by B. xylophilus inoculation. Slower growing P. pinea presented higher levels of constitutive defences than faster growing P. pinaster, with only P. pinaster being affected by B. xylophilus. Furthermore, co‐evolution with the pathogen is important, with the fast‐growing NA P. radiata presenting an inducible and effective response to B. xylophilus. Results point to the importance of integrating data on pine life history traits, including growth rate, and production of constitutive and inducible defences, into predictive models for this invasive forest pest.     

Growth environment and seedling age affect constitutive and inducible defence in radiata pine

There is increasing interest in induced resistance for crop protection. This study investigated effects of growth environment on inducible defences in developing radiata pine (Pinus radiata) seedlings. Seedlings were grown in the presence or absence of Trichoderma in either a temperature-controlled growth room or in a greenhouse. After 3, 5 or 7 months, seedlings were sprayed with 2.25 mm methyl jasmonate (MJ), 1 week before quantification of monoterpenes and total phenolics. The magnitude of induction of monoterpenes and total phenolics by MJ was inversely proportional to constitutive content, was greater in the greenhouse than the growth room and was greater at 3 months than at 7 months. This may indicate a cost-saving strategy to limit defence induction once constitutive defence reaches a certain threshold. Growth room seedlings expressed greater constitutive resistance to terminal crook (Colletotrichum acutatum) and to diplodia dieback (Diplodia sapinea) than greenhouse plants, consistent with the relative differences in constitutive defence chemistry. Indeed, while MJ induced resistance to diplodia dieback in both environments, there was no difference in terminal crook incidence (4.1%) between MJ-treated and untreated seedlings in the growth room. By the end of the study, growth room seedlings had c. 70% more β-pinene in stems and 140% more total phenolics in needles than greenhouse plants but were 40% smaller, indicating a defence–growth trade-off. Trichoderma did not have a significant effect on defence chemistry or on pathogen resistance. These results demonstrate the potential to manipulate defence in radiata pine by modification of the growth environment.     

Early investigations into the infection courts used by <Emphasis Type="Italic">Neonectria fuckeliana</Emphasis> to enter <Emphasis Type="Italic">Pinus radiata</Emphasis> stems

Nectria flute canker is a disease of Pinus radiata stems caused by the pathogen Neonectria fuckeliana occurring in the southern parts of New Zealand. In Northern Hemisphere countries where N. fuckeliana is endemic, it is commonly found in Picea and Abies spp. Open wounds, dead attached branches and branch stubs have been identified as the primary infection courts. Although in New Zealand the development of Nectria flute canker disease is associated with pruned branch stubs, recent studies suggest that this is not the only possible entry method as the fungus has been found in trees prior to pruning. Three field trials were established to examine the potential infection mechanisms for N. fuckeliana in P. radiata in New Zealand; including stem wounds and branch stubs. The difference between inoculations into the stem and into branch wood was clear. Inoculation of deep stem wounds resulted in the greatest fluting with 76% of trees inoculated developing cankers. Inoculation directly into stubs resulted in only small stem depressions that occurred in 17% of cases and the fungus was largely contained within the branch trace. Tree response to inoculation with either ascospores or conidia of the Acremonium anamorph gave similar results in terms of canker development and fungal spread within the stem. Tree response to inoculation was highly variable however: in one study 6% of trees did not respond to inoculation at all, while 26% produced severe cankers regardless of inoculation method. A more thorough understanding of the infection mechanisms of N. fuckeliana will contribute to the development of better disease management protocols to prevent infection and disease development in future plantation stock.     

New insights into radiata pine seedling root infection by Fusarium circinatum

Pine root infection by Fusarium circinatum has been reported in the literature, but the underlying pathogenic interaction is poorly understood. A green fluorescent protein (GFP)‐tagged F. circinatum isolate, together with confocal microscopy, was used in order to monitor the events associated with root infection of Pinus radiata seedlings. It was found that in order to reach and successfully infect pine roots, F. circinatum employed features that are similar to those previously described for other root‐infecting pathogens, such as mycelial strands, single runner hyphae and simple hyphopodia as well as other features that are reminiscent of those that are known to be involved in biotrophic invasion, such as bulbous invasive hyphae and filamentous invasive hyphae. Abundant sporulation was observed at the root surface as well as inside tracheids both in roots and in the root collar region. The fungus can spread from the roots to the aerial parts of the plant, and once there, colonization appears to be similar to the process that occurs when the pathogen is inoculated in the stem. Wilting symptoms and plant demise may be the result of a reduction in water uptake by roots and of the blockage of the vascular system by fungal hyphae and resin.     

Nematophagous Verticillium spp. in soils infested with Meloidogyne spp. in Cuba: Isolation and screening

Root-knot nematodes cause substantial economic loss of yield in coffee plantations and vegetable crops in Cuba. At present, methods to control the nematodes are ineffective or inappropriate and alternatives are being sought. The nematophagous fungus Verticillium chlamydosporium (Goddard) was isolated from soils collected from coffee plantations and infected root-knot nematode eggs from roots of tomato plants grown in these soils. A total of 83 isolates were collected and identified morphologically as V. chlamydosporium var. chlamydosporium, V. chlamydosporium var. catenulatum, V. psalliotae, V. suchlasporium and an isolate of V. chlamydosporium var. chlamydosporium with unusually large dictyochlamydospores. From these, 24 that represented a range of origins were selected and screened for their ability to parasitize eggs of root-knot nematodes, colonize the rhizosphere of barley roots and produce chlamydospores. None of the isolates grew at temperatures below 15°C and V. suchlasporium grew at a faster rate at lower temperatures than the other isolates. These were also screened in the glasshouse and V. chlamydosporium var. catenulatum caused the greatest reduction in nematode populations. One isolate of each subspecies of V. chlamydosporium was tested with the standard, Rothamsted isolate 10, on a range of host plants. The greatest reduction in numbers of nematodes occurred on tomato plants (cv. Pixie). The Rothamsted isolate 10 reduced numbers of nematodes toa greater extent than the other isolates, and therefore has the greatest potential as a biological control agent of root-knot nematodes.     

Electrophysiological and behavioural responses of Pityophthorus pubescens (Coleoptera: Scolytinae) to (E,E)‐α‐farnesene, (R)‐(+)‐limonene and (S)‐(−)‐verbenone in Pinus radiata (Pinaceae) stands in northern Spain

BACKGROUND: Some twig beetles in the genus Pityophthorus (Coleoptera: Scolytinae) may vector pitch canker disease Fusarium circinatum (Niremberg & O'Donnell) of Pinus spp. (Pinaceae). Because Pityophthorus pubescens (Marsh.) has been found to be associated with F. circinatum in the Basque Country (northern Spain), various experiments were conducted to assess the beetle's behavioural responses to (E, E)‐α‐farnesene, (R)‐(+)‐limonene and (S)‐(?)‐verbenone to develop a potential inhibitor to host attraction. These experiments comprise electroantennographic and double‐choice olfactometer tests, as well as field assays in Pinus radiata D. Don stands. RESULTS: Both sexes of P. pubescens showed similar electroantennographic responses to different doses (from 1 ng to 1 µg in decadic steps) of each individual compound, with depolarisations to (S)‐(‐)‐verbenone (100 ng) being similar to those of the aggregation pheromone (+)‐trans‐pityol. In olfactometer assays, both sexes were significantly attracted to (+)‐trans‐pityol, but the attraction was reduced when increasing amounts of the chemicals were added to the pheromone. Particularly relevant was the repellent effect induced by (S)‐(?)‐verbenone at 1 ng dose and higher. In the field, (E, E)‐α‐farnesene, (R)‐(+)‐limonene and (S)‐(?)‐verbenone reduced significantly the number of beetles attracted to (+)‐trans‐pityol and racemic trans‐pityol, with (S)‐(?)‐verbenone being the most effective. CONCLUSIONS: (S)‐(?)‐Verbenone showed an interesting potential for use in the protection of P. radiata stands. A potentially effective strategy, which could be implemented in further, more in‐depth studies, could involve the use of this semiochemical as repellent and (+)‐trans‐pityol‐baited traps as attractant in a ‘push‐pull’ strategy. Copyright © 2012 Society of Chemical Industry     

The potential protective value of ants in Northern Australian coffee plantations

Abstract

Native ants are the oldest example of biological control agents used in tropical tree crops. Unfortunately, intensification of agricultural practices has led to a simplification of habitat and subsequent loss of native ant biodiversity. This article describes research that evaluated the native and introduced ants present in the canopies of two Australian sun coffee plantations, their distribution pattern and their potential to limit pests. The presence in coffee plantations of a range of beneficial insects and parasites, plus the effect of ants, most notably Iridomyrmex suchieri Forel, may maintain potential pests at low levels in coffee plantations. These effects may be important for future biological control programs of coffee pests in Australia, although the sun coffee grown here does not harbor a large variety of canopy ant species.     

Economic criteria in the choice of weed-control methods for young pine (Pinus caribaea var. hundurensis Barr and Golf) plantations

The effect of three types of cover crop Calapogonium mucunoides Desv., Centrosema pubescens Benth. and Pueraria phaseoloides (Rexb.) Benth., and hand-weeding on the growth and yield of Pinus caribaea var. hundurensis Barr and Golf were investigated after 42 months of planting. The costs and benefits of the four methods are evaluated and compared. Results show no significant differences in survival percentage, but show significant differences in mean height of trees after 15 months. Survival percentage, mean height, girth and basal area of trees, measured after 42 months, showed no significant difference between treatments. However, trees grown with C. mucunoides had the highest values of all four variables measured. Economic analysis shows that cost per hectare is higher for hand-weeding while cover cropping has a higher net present value of investment. The results demonstrate that cover cropping is a more profitable alternative to hand-weeding in weed control in pine plantations, and that C. mucunoides will be the best choice of the three cover crops studied. Critères de choix économiques pour des méthodes de désherbage des jeunes plantations de pins (Pinus caribaea var hundurensis Barr and Golf) Les effets de 3 sortes de couvert végétal (Calapo-gonium mucunoides Desv., Centrosema pubescens Benth. et Pueraria phaseoloides (Rexb.) Benth. et du desherbage manuel sur la croissance et le rendement de Pinus caribaea var. hundurensis Barr et Golf ont étéétudiés après 42 mois de plantation. Les coûts et profits des quatre méthodes sont estimés et comparés. Les résultats ne montrent pas de différences significatives dans le pourcentage de survie, mais en revanche les différences sont significatives sur la hauteur moyenne des arbres après 15 mois. Le pourcentage de survie la hauteur moyenne, la surface basale et la circonférence des arbres mesurés après 42 mois n'expriment pas de différence significative entre les traitements. Cependant, les arbres élevés avec C. mucunoides ont des valeurs plus élevées pour les quatre variables envisagées. L'analyse économique montre que le coût par hectare est plus élevé pour le dèsherbage, tandis que le couvert végétal a une plus grande valeur nette d'investissement. Les résultats démontrent que le couvert végétal est une alternative plus rentable que le dèsherbage manuel dans les plantations de pins et que C. mucunoides est le meilleur choix parmi les trois espèces étudiées. L'analyse économique montre que le coût par hectare est plus élevé pour le désherbage manuel, tandis que le couvert végétal a une plus grande valeur nette d'investissement. Les résultats démontrent que le couvert végétal est une alternative plus rentable que le désherbage manuel dans les plantations de pins et que C. mucunoides est le meilleur choix parmi les 3 espèces étudiées. Ökonomische Kriterien für die Unkrautbekämpfung in Kulturen von Pinus caribaea var. hundurensis Barr & Golf Die Wirkung von Bodendeckern (Calapogonium mucunoides Desv., Centrosema pubescens Benth., Pueraria phaseoloides (Rexb.) Benth., und mechanischer Unkrautbekämpfung (Jäten) auf das Wachstum und den Zuwachs von Pinus caribaea var. hundurensis Barr & Golfwurde 42 Monate nach der Pflanzung untersucht. Die Kosten und die Wirksamkeit der 4 Varianten wurden verglichen. Während hinsichtlich des Anwachsens keine Unterschiede bestanden, ergaben sich für die mittlere Wuchshöhe der Bäume nach 15 Monaten signifikante Unterschiede. Überlebensrate, mittlere Höhe und Stammumfang waren 42 Monate nach der Pflanzung nicht significant verschieden, doch waren diese Parameter bei Calapogonium mucunoides am höchsten. Die Hektarkosten waren für die mechanische Unkrautbekämpfung höher als für die Bepflanzung mit Bodendeckern, die sich damit für Kiefernkulturen als wirtschaftlicher erwies. Von den 3 Bodendeckern ist die erstgenannte Art vorzuziehen.