Factors affecting the composition of pathogenic populations of Phytophthora cinnamomi as a root pathogen of native plants in natural forests in Victoria.

Disease within an open sclerophyll forest dominated by Eucalyptus species of relatively low stature (15-20 m) was shown to be caused by Phytophthora cinnamomi Rands, an introduced root pathogen. Diseased sites were mapped and measured. The rate of advance of the pathogen over a period of 5 months was calculated at 4 m per month through moderately drained soils compared with 7 m per month through soils subject to waterlogging. Areas showing disease symptoms increased from 10.8 to 90%, the major extensions occurring along gullies. Spread of the fungus was associated with road-making activities, waterlogging, and the presence of drainage channels. Symptom expression in the different species was studied and shown to be similar to that associated with water stress. Most of the 42 species comprising the woody flora were susceptible to the disease, those particularly susceptible including the dominants. During a period of 8 months mortalities occurred in 50% of the species. Grasses, sedges, and Eucalyptus goniocalyx appeared to be field-resistant, but were uncommon in the Aora of the sites studied.

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Factors Affecting Timber Production in Akwa Ibom State (Nigeria) and the Way Forward

Asian Journal of Research in Agriculture and Forestry ◽

10.9734/ajraf/2020/v6i330107 ◽

2020 ◽

pp. 31-40

Author(s):

N. E. Esiere ◽

N. B. Ndulue ◽

M. P. Akpan

Keyword(s):

Private Sector ◽

Sustainable Management ◽

Standing Stock ◽

Timber Harvesting ◽

Forest Resources ◽

The State ◽

Timber Production ◽

Natural Forests ◽

Factors Affecting ◽

The Way

In Akwa Ibom State, timber is used for building, construction, furniture making, transmission pole, pulp and paper, and chemicals. Timber harvesting, processing and utilization had remained a big business to quite a number of people with its attendant forest destruction and deforestation. The State was richly endowed with forest resources, which are of great benefit to man but the high demand and continuous harvesting of timber products in the State ecosystems without any deliberate sustainable management programmes has resulted in the over-harvesting and complete devastation of the standing stock of indigenous wood species. In addition, indiscriminate exploitation of these resources has caused depletion of forest leading to serious timber deficit. This work has discussed factors affecting timber production in Akwa Ibom State and the way forward. The paper has identified deforestation and ‘dereservation’, overexploitation of forest resources, revenues target by government, population growth and infrastructure expansion, non-participation of the private sector in forest development, amongst others, as factors responsible for the decline of timber resources in the state. The paper recommends that reforestation and afforestation programmes, conservation of natural forests, private sector participation in forest management, adoption of agroforestry system and sustainable management of natural resources can improve timber production in the State.

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Factors Affecting the Population Density of Phytophthora cinnamomi in Native Forests of the Brisbane Ranges, Victoria.

Australian Journal of Botany ◽

10.1071/bt9750077 ◽

1975 ◽

Vol 23 (1) ◽

pp. 77 ◽

Cited By ~ 5

Author(s):

G Weste ◽

P Ruppin

Keyword(s):

Phytophthora Cinnamomi ◽

Ground Cover ◽

Wood Production ◽

Population Densities ◽

Pathogen Population ◽

Recent Infection ◽

Factors Affecting ◽

Disease Extension ◽

Open Woodland

Population densities of Phytophthora cinnamomi Rands were measured at 10-day intervals during a period of 13 months at three sites in the Brisbane Ranges. Statistical analyses of results and of simultaneous metereological measurements demonstrated that both low temperatures and dry soils were correlated with a significant decrease in pathogen population. Disease extension occurred uphill on a slope of 4" at 6 . 6 m per year, but only from recent infection. Population densities of older sites were significantly less than that of the new site and no measurable disease extension occurred uphill from them. Disease caused an immediate and continuing reduction in understorey in both the number of species and the ground cover and, in the long term, a reduction in both wood production and the number of trees as the dense dry sclerophyll shrubby forest was changed to an open woodland.

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Mefenoxam Sensitivity in Phytophthora cinnamomi Isolates

Plant Disease ◽

10.1094/pdis-94-1-0039 ◽

2010 ◽

Vol 94 (1) ◽

pp. 39-44 ◽

Cited By ~ 16

Author(s):

Jiahuai Hu ◽

Chuanxue Hong ◽

Erik L. Stromberg ◽

Gary W. Moorman

Keyword(s):

Woody Plant ◽

Phytophthora Cinnamomi ◽

Uv Mutagenesis ◽

Mycelium Growth ◽

Root Pathogen ◽

Highly Sensitive ◽

Plant Nursery ◽

Mycelial Plug

Phytophthora cinnamomi is a destructive root pathogen of numerous woody plant species in the ornamental plant nursery. Sixty-five isolates of P. cinnamomi were evaluated for mefenoxam sensitivity on 20% clarified V8 agar amended with mefenoxam at 0 or 100 μg/ml. In the presence of mefenoxam at 100 μg/ml, eight isolates were intermediately sensitive, with mycelium growth ranging between 11 and 18% of the nonamended control, and 57 isolates were highly sensitive, with little or no mycelium growth. Five intermediately sensitive and five sensitive isolates were chosen to characterize their responses to mefenoxam at 0, 0.1, 1, 10, and 100 μg/ml. For intermediately sensitive isolates, the mefenoxam concentration causing 50% inhibition of mycelium growth (EC50 values) ranged between 0.03 and 0.08 μg/ml; EC50 values for sensitive isolates varied from 0.01 to 0.02 μg/ml. Five intermediately sensitive and seven sensitive isolates were selected further to assess in vivo sensitivity to mefenoxam using Lupinus angustifolius ‘Russell Hybrids’. Lupine seedlings were treated with distilled water or mefenoxam at label rate (Subdue MAXX, 1 fl. oz. of product per 100 gal.) and then, 2 days later, inoculated with a 5-mm-diameter mycelial plug of P. cinnamomi on each cotyledon. Mefenoxam-treated plants averaged more than 96% less disease than water-treated plants. Mefenoxam provided adequate protection of lupines from infection by all 12 isolates regardless of their in vitro levels of sensitivity to mefenoxam. The ability to develop mefenoxam resistance was assessed in P. cinnamomi isolates with different mefenoxam sensitivity by UV mutagenesis and adapting mycelium to increasing concentrations of mefenoxam. Both UV mutagenesis and mycelium adaptation generated isolates with reduced sensitivity to mefenoxam. These isolates, however, did not grow as quickly as their corresponding parent. This study suggests that P. cinnamomi populations from ornamental nurseries in Virginia are sensitive to mefenoxam.

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Periodicity of Fine Root Growth in Jarrah (Eucalyptus marginata Donn Ex Sm.)

Australian Journal of Botany ◽

10.1071/bt9830247 ◽

1983 ◽

Vol 31 (3) ◽

pp. 247 ◽

Cited By ~ 13

Author(s):

B Dell ◽

IM Wallace

Keyword(s):

Root Growth ◽

Fine Root ◽

Phytophthora Cinnamomi ◽

Late Summer ◽

Late Winter ◽

Summer Drought ◽

Root Pathogen ◽

Eucalyptus Marginata ◽

Fine Root Growth ◽

Mycorrhizal Roots

The timing of new surface root growth in jarrah (Eucalyptus marginata) was followed for a 15-month period in the field. The periodicity of new root growth was similar for long roots, non-mycorrhizal and mycorrhizal root clusters. Root growth was initiated during two peak periods in spring (September-October) and following autumn rain (May-June). Little new root activity was recorded in late winter (August) or during summer drought. Rapid root growth occurred within 2 days of a storm (47 mm rain) in February. In addition, short roots formed after very light showers of rain (<5 mm) in late summer. Much of the framework for fine feeder roots was built up after autumn rain. In contrast to new long root growth which was equally spread between spring and late autumn, the majority of new mycorrhizal roots were produced from May to July. Root growth ceased when warm surface soils dried out and commenced when the soils were moist after rain. Much of the new root growth in jarrah occurred when the root pathogen Phytophthora cinnamomi was active in the soil.

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Preventing Death and Taxus: Review and Recommendations for Managing Taxus in the Landscape with Overview on Phytophthora cinnamomi, Soil, and Nutrition Status

Arboriculture & Urban Forestry ◽

10.48044/jauf.2014.032 ◽

2014 ◽

Vol 40 (6) ◽

Author(s):

Matthew Taylor

Keyword(s):

Best Management Practices ◽

Management Practices ◽

Cultural Practices ◽

Phytophthora Cinnamomi ◽

Critical Factor ◽

Nutrition Status ◽

Root Pathogen ◽

Best Management ◽

The Usa ◽

Longterm Survival

At least three major gardens or arboreta in the USA have experienced periods of significant decline and death of mature Taxus (yews) in the landscape. The symptoms displayed on declining plants are described as chlorosis of the needles, partial defoliation, and death of some of the branches. Eventually, the entire plant may die, but they are typically removed before reaching this stage. Information on managing mature Taxus in the landscape is limited. The objective of this article is to review the literature on Taxus cultural practices and use the information to develop best management practices for Taxus in the landscape. Soil moisture is the most critical factor for health of plants in the landscape. Saturated soils create anaerobic conditions for roots and create an environment ideal for root infection by Phytophthora cinnamomi, the major root pathogen affecting Taxus. During planting, proper site selection and well-drained soil are crucial for the longterm survival of plants. After planting, irrigation should be managed to avoid saturated soil. Management from a nutritional standpoint is poorly understood. Maintaining an appropriate pH of 6.0 to 7.0 and fertilizing plants based on soil and tissue testing is recommended. More research needs to be done to determine optimal fertilization rates and appropriate nutrient concentration in tissue and in soil. When plants become symptomatic, soil should be tested for P. cinnamomi. If the fungus is present, appropriate chemical controls should be used.

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Factors Affecting Lichen Diversity in Manor Parks of Pskov Region (Northwestern Russia)

The Bulletin of Irkutsk State University Series Biology Ecology ◽

10.26516/2073-3372.2021.35.19 ◽

2021 ◽

Vol 35 ◽

pp. 19-33

Author(s):

N. B. Istomina ◽

◽

O. V. Likhacheva ◽

Keyword(s):

Species Diversity ◽

Species Composition ◽

Lichen Species ◽

Species Number ◽

Dispersion Pattern ◽

Natural Forests ◽

Forest Zone ◽

Factors Affecting ◽

Lichen Diversity ◽

The Impact

The article describes the results of studies of the factors affecting lichen diversity in 46 manor parks of the region of Pskov. The investigated parks were founded in the end of XVIII – beginning of XX centuries. Twenty of them are fragmented and currently occupy less than 5 ha, the area of nine parks varies from 5 to 10 ha, those preserved within historical boundaries cover from 11 to 100 ha. Manor parks are situated both within the settlements’ boundaries (31 parks) and outside the settlements either bordering forest (12) or agricultural lands (3). Ten of the former border the forests. During the study 166 lichen species were identified. Statistical methods were performed to investigate the factors affecting lichen diversity in manor parks. Linear regression analysis was used to examine the dependence of the lichens species number on the park age/date of park creation (dispersion pattern), area of the parks (box plot), substrata diversity (dispersion pattern), and the dependence of the epiphytic lichens species number on tree and shrub species diversity (dispersion pattern). With the biserial correlation coefficient the impact of the settlement and the presence of the surrounding natural forests was calculated. Correlation analysis was performed to demonstrate the colligation between lichen species composition of the parks located in different subzones of forest zone in the region of Pskov. Our findings show that the number of lichen species depends on the park area (p = 0,0315), the variety of substrate types (p ˂ 0,001), and the variety of trees and bushes planted (p ˂ 0,001). The date of park creation and the presence of the surrounding natural forests do not influence the species diversity of lichens. We reveal that the location of the parks in a specific subzone of forest zone (southern taiga and mixed coniferous-broad-leaved forest) has no significant effect on the lichen species composition. The species richness of lichens tends to decrease in parks located within the settlements. The data obtained indicate not only the similarity of the species composition of lichens in the studied communities, but also the long-term development of lichen park communities in comparable climatic and landscape conditions.

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