THE STUDY OF THE ECONOMIC THRESHOLD OF TOMICUS PINIPERDA (COLEOPTERA: SCOLYTIDEA) ON YUNNAN PINE

Abstract By careful and long period field investigation of the population density of Tomicus piniperda L. and the growth of Yunnan pine ( Pinus yunnanensis French.), and improved regression analysis, the economic threshold of Tomicus piniperda on Yunnan pine is determined: When the death rate of the trees is not more than 0.52%, the natural control factors can prevent the density of the bark beetle from increasing and no control measure is needed. When the death rate of the trees reaches 0.5%, the corresponding rate of shoots attacked is 0.61% and the mean of invading holes per tree 0.66, the cost for control is equal to the economic loss saved. So, considering both the economic justification and the prevention of the pest density from increasing, when the death rate of the trees is more than 0.5%, the corresponding rate of shoots attacked more than 0.61% and the mean of invading holes per tree more than 0.66, control measure should be taken. The paper also gives formulae for different Yunnan pine forest areas to calculate their own economic threshold according to their special situations.     

为害云南松的纵坑切梢小蠹 (Tomicus piniperda)经济阈值的研究(英文)

经过对纵坑切梢小蠹 (TomicuspiniperdaL .)种群密度和云南松 (PinusyunnanensisFranch .)生长状况的长期、仔细的调查 ,加上改进的回归分析方法 ,得出了为害云南松的纵坑切梢小蠹防治上的经济阈值 :当林木枯死率不超过 0 .5 2 %时 ,自然控制因子能控制纵坑切梢小蠹种群不向高密度方向发展 ,因而可以不必防治。当林木枯死率达到 0 .5 0 % ,对应的枯捎率为 0 .6 1 % ,以及对应的平均每株侵入孔数为 0 .6 6时 ,防治费用和挽回损失价值相当。所以 ,若既考虑到经济上的合理性 ,又考虑到控制其种群不向高密度方向发展 ,当林木枯死率超过 0 .5 % ,对应的枯梢率超过 0 .6 1 % ,以及对应的平均每株侵入孔数超过 0 .6 6时 ,就有了进行防治的必要。本文还给出了各云南松林区可以用来根据自己的具体情况计算出适合自己的经济阈值的公式。     

Endophytic fungal diversity in Theobroma cacao (cacao) and T. grandiflorum (cupuaçu) trees and their potential for growth promotion and biocontrol of black-pod disease

The endophytic niches of plants are a rich source of microbes that can directly and indirectly promote plant protection, growth and development. The diversity of culturable endophytic fungi from stems and branches of Theobroma cacao (cacao) and Theobroma grandiflorum (cupua?u) trees growing in the Amazon region of Brazil was assessed. The collection of fungal endophytic isolates obtained was applied in field experiments to evaluate their potential as biocontrol agents against Phytophthora palmivora, the causal agent of the black-pod rot disease of cacao, one of the most important pathogens in cocoa-producing regions worldwide. The isolated endophytic fungi from 60 traditional, farmer-planted, healthy cacao and 10 cupua?u plants were cultured in PDA under conditions inducing sporulation. Isolates were classified based upon the morphological characteristics of their cultures and reproductive structures. Spore suspensions from a total of 103 isolates that could be classified at least up to genus level were tested against P. palmivora in pods attached to cacao trees in the field. Results indicated that ～70% of isolates showed biocontrol effects to a certain extent, suggesting that culturable endophytic fungal biodiversity in this system is of a mostly mutualistic type of interaction with the host. Eight isolates from genera Trichoderma (reference isolate), Pestalotiopsis, Curvularia, Tolypocladium and Fusarium showed the highest level of activity against the pathogen, and were further characterized. All demonstrated their endophytic nature by colonizing axenic cacao plantlets, and confirmed their biocontrol activity on attached pods trials by showing significant decrease in disease severity in relation to the positive control. None, however, showed detectable growth-promotion effects. Aspects related to endophytic biodiversity and host-pathogen-endophyte interactions in the environment of this study were discussed on the context of developing sustainable strategies for biological control of black-pod rot of cacao.     

Fruit trees in a Malaysian rain forest

An inventory was made of 50 ha of primary lowland rain forest in Peninsular Malaysia, in which ca. 340,000 trees 1 cm dbh or larger were measured and identified to species. Out of a total plot tree flora of 820 species, 76 species are known to bear edible fruit. Especially diverse were the wild species of mango (Mangifera, Anacardiaceae, 12 spp.), mangosteen (Garcinia, Clusiaceae, 13 spp.), breadfruit (Artocarpus, Moraceae, 10 spp.) and rambutan (Nephelium, Sapindaceae, 5 spp.). Median population size for all species of fruit trees was 3.0 trees per ha and 0.2 adult trees per ha. Direct economic value of wild fruit trees was small; only one species has been very much collected and sold, Parkia speciosa (Fabaceae), amounting to less than US$20 per ha per year. The potential value of the species as genetic resources is very large: 24 species are cultivated, 38 edible species are congeneric with cultivated crops and at least 10 other species bear inedible fruit but are related to cultivated crops. We conclude that the Peninsular Malaysian rain forest is exceedingly rich in wild fruit trees, that these normally live at low densities, and that their principal economic value is as genetic resources.     

Elution rate and spacing of antiaggregation pheromone dispensers for protecting live trees from Dendroctonus pseudotsugae (Coleoptera: Scolytidae)

The antiaggregation pheromone 3-methylcyclohex-2-en-1-one (MCH) is highly effective in preventing the infestation of high-risk trees by Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins. A large portion of the cost of an MCH treatment is related to the time applicators spend walking through an area dispersing the formulated pheromone. Application of fewer MCH dispensers eluting at a higher rate than those currently registered for operational use could potentially reduce treatment costs. Two higher elution rates, 6 and 18 mg/d per dispenser, were compared with the current standard of 2 mg/d per dispenser and an untreated control on 1-ha circular plots. Dispensers were spaced 5,15, and 44 m apart around the plot perimeters eluting 2, 6, and 18 mg/d, respectively. The nominal dose of MCH was 144 mg/ha/d on all plots. Percentages of Douglas-fir trees > or = 20 cm diameter at breast height mass attacked by Douglas-fir beetle were significantly lower on plots treated with dispensers eluting 2 and 6 mg/d and spaced 5 and 15 m apart, respectively, compared with the untreated control. Infestation rate on plots treated with dispensers eluting 18 mg/d and spaced 44 m apart was not significantly different from the control. Douglas-fir beetle abundance and host tree availability were similar on all plots. These results indicate that MCH dispensers eluting 6 mg/d (three times the current standard rate) and spaced 15 m apart (three times existing standard distance) can effectively prevent Douglas-fir beetle infestations.     

EXPERIMENTS ON SPRAYING WITH DDT TO PREVENT THE FEEDING OF SCOLYTUS BEETLES ON ELM AND CONSEQUENT INFECTION WITH CERATOSTOMELLA ULMI

Experiments were done for three years on street elms at Folkestone and Aldenham to repeat American work on the use of insecticidal sprays to prevent feeding by Scolytus beetles, which carry Ceratostomella ulmi , the cause of elm disease. Although the fungus can remain alive in the older annual rings of an infected tree, active disease usually results from fungus freshly introduced by Scolytus. Thus spraying is of value on infected, as well as uninfected elms.
The results of the experiments supported American conclusions that DDT was superior to benzene hexachloride. A 1.5% solution of DDT in miscible oil gave reasonably good, but not perfect, control, and was much superior to solutions made from DDT in the form of a dispersible powder.
Spraying of trees 20–30 ft. high cost over £1 per tree per year, which is considered prohibitive, except for small trees of special amenity or sentimental value.     

Effects of row and plant spacing and time of planting on seed yield of kenaf

Plants of kenaf (Hibiscus cannabinus L.), grown in southern Florida in 1964, yielded significantly more seed when spaced 5 inches apart in 7-inch rows than when spaced farther apart, up to 15 × 28 inches. Plants grown from seed planted on August 10 yielded significantly more seed than those from seed planted later at 10-day intervals, from August 20 to September 29. A progressive decline in yield was associated with wider plant-and-row spacmgs and with later plantings.     

Reduced oviposition by Diaprepes abbreviatus (Coleoptera: Curculionidae) and growth enhancement of citrus by Surround particle film

Regularly applied sprays of a particle film, Surround WP, greatly enhanced the growth of citrus trees on a poorly drained Winder soil at Fort Pierce, FL. After 3 yr of applications every 3 or 4 wk, Surround-treated trees had at least 5 times the mass, 6 times the canopy volume, and approximately 4 times the cross-sectional area of the tree stems at the graft union compared with untreated trees. The larger Surround-treated trees attracted a higher number of adult weevil Diaprepes abbreviatus (L.) and to a lesser extent citrus root weevil, Pachnaeus litus (Germar), per tree, but there was an equivalent number of egg masses per tree compared with the control trees. The number of egg masses per female weevil oviposited on Surround-treated trees was significantly less than either the control trees or trees treated biannually with an entomopathogenic nematode, BioVector. The number of larvae per tree recovered from the roots of excavated trees was greater from trees treated with Surround once every 3 wk compared with control trees. The data suggest that Surround particle film greatly enhanced the growth of citrus trees grown in a poorly drained soil. The reduction in oviposition by D. abbreviatus was insufficient to significantly reduce the number of root weevil larvae per tree feeding on the roots. However, the more vigorous trees resulting from Surround applications may be more resistant or tolerant to root weevil feeding.     

VIRUS DISEASES OF CACAO IN WEST AFRICA IX. STRAIN VARIATION AND INTERFERENCE IN VIRUS 1A

Cacao virus iA, the most important and prevalent of the viruses that attack cacao in the Gold Coast, occurs in strains that differ widely in their virulence towards cacao. Outbreaks usually contain trees infected with different strains and individual trees are often infected simultaneously with more than one strain; this can be demonstrated by coppicing the trees, and by inoculating sets of test plants with grafts from different parts of one tree. Neither mild nor virulent strains seemed to be consistently dominant in roots or in other parts of cacao trees.
Cacao plants infected with mild strains were nearly always protected against the effects of infection by virulent strains; however, virulent strains entered hosts already infected with mild strains, but usually without causing any symptoms unless the plants were coppiced. The severe symptoms that developed on new growth from such coppiced plants were seldom repeated in later growth. Mealybugs transmitted the virulent strains from leaves with symptoms characteristic of infection by the latter, but not from leaves free from such symptoms. These results suggest that the multiplication of a virulent strain is impeded in plants infected with a mild strain.
In the field, infection with a mild strain protected mature trees against the effects of virulent strains spread by mealybugs. During 3 years in which 273 out of 387 previously uninfected trees became severely diseased, only 35 out of 416 infected with themildstrain developed symptoms of infectionwiththevirulent strain. Five years after infection with the mild strain, trees were yielding I pod per tree more than in the year they were infected, whereas the decrease on trees infected with the virulent strain was 16 pods per tree. Some limitations in the practical application of protection by mild strains, and objections to its use as a control measure, are discussed.     

Studies of Fruit Development of Cacao (Theobroma cacao) in Relation to Cherelle wilt: III. Effects of fruit-thinning

Cacao trees were manually thinned to 1, 2, or 10 pods per treein order to observe the effect of competition onwilting behaviour.The number of pods wilting and harvested were recorded weeklyfor I6 months. The percentage of pods that wilted on the thinnedtrees was less than the controls. However, yields were reducedon the thinned trees more than expected owing to the continuedwilting of those pods left on the trees. The results supportthe hypothesis that cherelle with is a fruit thinning mechanism,but that biotic factors can cause the same syndrome.     

Production ecology of CopaÍba (Copaifera spp.) oleoresin in the eastern brazilian Amazon

Oleoresin extracted from copaiba (Copaifera spp.: Leguminosae) trees is a popular traditional medicine in Amazonia. I studied production ecology from three copaiba types in the eastern Brazilian Amazon. Mean oleoresin yield from the first harvest was 0.07 liters per tree for all trees drilled and 0.23 liters per tree for ones yielding some oleoresin. Yields were comparable toC. multijuga results in central Amazonia but lower than anecdotal reports of 2 liters or more per tree. Yield differences were minor between tree types and seasons. Yield peaked in mid-size trees (45-65 cm DBH) while small (45 cm DBH), very large (>65 cm DBH), and hollow trees (due to senescence or fire) yielded negligible amounts. Oleoresin was harvested almost exclusively from inner heartwood, indicating that factors stimulating its synthesis in cambium are probably distinct from factors that promote its storage in heartwood and loss of yield many years later.     

A multiyear estimate of the effective pollen donor pool for Albizia julibrissin

Studies of pollen movement in plant populations are often limited to a single reproductive event, despite concerns about the adequacy of single-year measures for perennial organisms. In this study, we estimate the effective number of pollen donors per tree from a multiyear study of Albizia julibrissin Durazz (mimosa, Fabaceae), an outcrossing, insect-pollinated tree. We determined 40 seedling genotypes for each of 15 seed trees during 4 successive years. A molecular analysis of variance of the pollen gametes fertilizing the sampled seeds was used to partition variation in pollen pools among seed trees, among years, and within single tree-year collections. Using these variance components, we demonstrate significant male gametic variability among years for individual trees. However, results indicate that yearly variation in the 'global pollen pool', averaged over all 15 seed trees for these 4 years, is effectively zero. We estimate the effective number of pollen donors for a single mimosa tree (N(ep)) to be 2.87. Single season analyses yield N(ep) approximately 2.05, which is 40% less than the value of N(ep) estimated from 4 years of data. We discuss optimal sampling for future studies designed to estimate N(ep). Studies should include more trees, each sampled over at least a few years, with fewer seeds per tree per year than are needed for a traditional parentage study.     

Crop Growth, Disease and Yield Components of Rusted Phaseolus Beans in Ethiopia

Crop growth and disease epidemics in sprayed and non-sprayed bean plots, artificially infected with rust (Uromyces appendiculatus) 3 weeks after emergence. were assessed weekly in two cultivars, at two locations for two seasons. Disease intensity was regulated by the application of a fungicide at 5 spray frequencies. Fungicide application influenced leaf area index (LAI) and reduced rust intensity. The fungicide had no significant effect on other diseases and dead leaf area. Fungicide application increased seed yield (SY) by increased numbers of pods per plant (PP). Rust severity was strongly correlated with pustule density but the overall relationships among rust assessment parameters depended on cultivar and location. Seed yield and pods per plant were highly correlated with LAI. The relationships between LAI and seeds per pod or seed weight depended on cultivar and location. Overall rust assessment parameters (rust severity and pustule density) showed close, negative relationships with seed yield. seed weight and pods per plant but not with seeds per pod. The relationships obtained in the partially resistant line 6-R-395 were less definite than those in the susceptible line Mexican 142. The yield parameters seed yield and pods per plant, showed strong positive relationships.     

Effect of ascochyta blight (Mycosphaerella pinodes) on yield components of single pea (Pisum sativum) plants under field conditions

Field studies were made in 1992 and 1993 to examine the yield components of pea inoculated with Mycosphaerella pinodes and those of healthy pea (sprayed with a mixture of flutriafol + chlorothalonil), in a split-plot design with the cv. Solara sown at different plant densities. Ascochyta blight was severe on leaves and on internodes of the basal part of the plants; pods had few lesions. The number and length of stems per plant were the same for diseased and healthy plants. The number of reproductive nodes and pods per stem were affected by disease only in 1993. In 1992 and 1993 respectively, disease caused reductions in the number of seeds per stem of 18% and 25%, and in seed size of 13.5% and 16.7%, compared with healthy plants. The harvest index and total biomass were lower in diseased than in healthy plants and seed yield was reduced by 40% in diseased plots. These results show a high relationship between the disease parameters (disease mean on stipules/nodes 8–18/ and on internodes/nodes 5–15/, percentages of stipules or internodes with a disease score 4, and percentage of stems encircled by lesions), plant density and yield reduction.     

银杏主要病虫害综合治理技术研究

在广西桂林银杏产区,危害银杏的主要病虫害有银杏超小卷叶蛾、白蚁、叶枯病,植株受害后,树势生长衰弱,产量下降,尤其是百年银杏大树尤为明显。经过试验分析找出对上述病虫害进行治理的最佳技术措施是:采用施肥、抚育、修剪、清园等营林技术措施治本,药剂防治救急措施治标,以治本为主,标本兼治。试验结果:超小卷叶蛾的防治效果在92%以上,白蚁的防治效果达100%,叶枯病的防治效果在85.9%以上,平均单株产量比治理前增产20.3kg,增幅为94.8%,单株产量高于对照0.6倍,平均单株新梢量高于对照4.6倍。对示范区和推广区的治理树进行调查分析,共治理银杏大树14.58万株,平均每株增产银杏20.34kg,共增产银杏296.519万公斤,产值达4744.304万元,经济、社会、生态三大效益显著。     

Fruit Yield,not DBH or Fruit Crown Volume,Correlates with Time Spent Feeding on Fruits by Wild Leontopithecus rosalia

Assessing fruit availability is a critical element in testing hypotheses concerning resource use by frugivores. One method to estimate fruit availability is to measure tree diameter at breast height (DBH) and assume a positive correlation with fruit tree productivity. Our first objective was to test the relationship between DBH and tree productivity. We used as our measures of tree productivity: volume of the fruit bearing region of the tree crown (FBRv) and fruit yield measured as grams of dry fruit matter per fruit bearing region (FBR). Our second objective was to determine if time spent feeding on fruits by golden lion tamarins was correlated with 3 measures of tree productivity within their territories. We define tree productivity within a territory as tree productivity × tree density (fruit tree productivity/ha). We used as our measures of tree productivity/ha: (1) DBH × tree density, (2) fruit yield × tree density, and (3) FBRv × tree density. We measured DBH and FBRv for 17 fruit species commonly eaten by golden lion tamarins in Poço das Antas Reserve, Brazil. We counted fruits in trees and collected fruits to calculate fruit yield. We used measures of tree densities to calculate tree productivity/ha. We found that DBH correlated with fruit yield. The time tamarins spent feeding did not correlate with DBH ( × tree density) or FBRv ( × tree density), but it correlated with fruit yield ( × tree density). Our results emphasize the importance of recording temporal and spatial measures of fruit productivity that are meaningful to the frugivore studied.     

Epiphytic (including hemiepiphytes) diversity in three timber species in the southwestern Amazon, Brazil

Forestry managers have been searching for ways to reduce the impacts of logging on Amazonian biodiversity, but some basic factors are still not considered in native forestry operations, among them the diversity of epiphytes associated with the logged trees. Our goals in this study were to determine the floristic composition, quantify the species richness, and characterize the species diversity of the vascular epiphytic community present in three timber tree species in Acre State, Brazil. We collected and identified all epiphytes in 30 randomly selected trees ≥35 cm DBH of each of three important timber species, Tabebuia serratifolia, Manilkara inundata and Couratari macrosperma. We also documented the epiphyte diversity in 120 randomly selected trees ≥35 cm DBH of 56 other species to determine whether the three timber species have different epiphyte diversity than the tree community at large. The epiphyte samples in the three timber species showed 77 species, 13 of which were new records for the flora of Acre state. The epiphyte community in the randomly selected trees presented a total of 56 species. The timber species phorophytes hosted on average three times more epiphyte species per tree than the other 120 randomly selected trees. These results show that a substantial portion of local floristic richness can be lost during logging activity due if not properly managed by rescuing epiphytes after felling the trees. Although these epiphytes could contribute positively to forestry sustainability due to their ornamental value, increasing the economic yield per hectare, there are no local initiatives for economic use of epiphytes.     

Acorn production prediction models for five common oak species of the eastern United States

Acorn production varies considerably among oak (Quercus) species, individual trees, years, and locations, which directly affects oak regeneration and populations of wildlife species that depend on acorns for food. Hard mast indices provide a relative ranking and basis for comparison of within- and between-year acorn crop size at a broad scale, but do not provide an estimate of actual acorn yield—the number of acorns that can potentially be produced on a given land area unit based on the species, number, and diameter at breast height (dbh) of oak trees present. We used 10 years of acorn production data from 475 oak trees to develop predictive models of potential average annual hard mast production by five common eastern oak species, based on tree diameter and estimated crown area. We found a weak (R² = 0.08–0.28) relationship between tree dbh and acorn production per unit crown area for most species. The relationship between tree dbh and acorn production per tree was stronger (R² = 0.33–0.57). However, this is because larger-dbh trees generally have larger crowns, not because they have a greater capacity to produce more acorns per unit crown area. Acorn production is highly variable among individual trees. We estimated that dbh of at least 60 dominant or codominant oak trees per species should be randomly sampled to obtain an adequate representation of the range of dbhs (≥12.7 cm dbh) in a given forest area, and achieve precise estimates when using these equations to predict potential acorn production. Our predictive models provide a tool for estimating potential acorn production that land managers and forest planners can apply to oak inventory data to tailor estimates of potential average annual acorn production to different forest management scenarios and multiple spatial scales. © 2011 The Wildlife Society.     

The effects of cocoa swollen-shoot virus on the growth and yield of Amelonado and Amazon cocoa (Theobroma cacao) in Ghana

The virulent strain A of cocoa swollen-shoot virus (CSSV) severely decreased the growth and yield of Amelonado cocoa (Theobroma cacao) trees kept free of capsids (Distantiella theobroma and Sahlbergella singularis) and the dieback fungus (Calonectria rigidiuscula) in Ghana. Fifteen per cent of graft-inoculated Amelonado trees showed symptoms within 4 months, and 48, 80 and 100% within 6, 12 and 20 months, respectively. Infected trees, whether shaded or unshaded, began to decline 6 months after infection, and deteriorated rapidly during the next 27 months by which time 16 % had died and most others were moribund; fertilizer applications had no significant effect on the rate at which infected trees deteriorated. Yields of pods and dry cocoa were greatly reduced 2 yr after infection and were very low after 3 yr; yields were significantly reduced by virus infection but there were no significant further effects of applying fertilizer. These results confirm that CSSV strain A alone is very damaging and often eventually lethal to Amelonado trees in Ghana, and indicate that the conflicting results obtained previously in Ghana and Nigeria were probably due to differences in the virulence of the CSSV strains tested. In contrast, the virus had much less effect on cocoa trees of the Amazon type; only 3% of graft-inoculated Amazon trees showed symptoms within 4 months, and 43, 84 and 97% after 1, 2 and 3 yr, respectively. Slight deterioration of tree canopies was first detected c. 15 months after infection and, although it continued slowly during the next 21 months, the decline was much less severe than that of Amelonado trees. Yields of both unshaded and shaded trees were apparently reduced by virus infection, but yield losses were much smaller than those of Amelonado trees. These results support the present objectives of controlling the spread of CSSV in Ghana by roguing infected trees, and selecting cultivars with greater tolerance to infection for future use.     

Maximum tree: a consistent estimator of the species tree

We propose a model based approach to use multiple gene trees to estimate the species tree. The coalescent process requires that gene divergences occur earlier than species divergences when there is any polymorphism in the ancestral species. Under this scenario, speciation times are restricted to be smaller than the corresponding gene split times. The maximum tree (MT) is the tree with the largest possible speciation times in the space of species trees restricted by available gene trees. If all populations have the same population size, the MT is the maximum likelihood estimate of the species tree. It can be shown the MT is a consistent estimator of the species tree even when the MT is built upon the estimates of the true gene trees if the gene tree estimates are statistically consistent. The MT converges in probability to the true species tree at an exponential rate.