Chestnut Ink Disease Research Articles

CHESTNUT INK DISEASE AND PHOTOSYNTHETIC PRODUCTIVITY

Changes in photosynthetic relations associated with infection by Phytophthora cinnamomi were studied in inoculated plants of Castanea sativa (cv. Judia), many hybrid clones (C. crenata × C. sativa) and the ink disease resistant COLUTAD. The aim of this work is to analyse the effect of the inoculation of the ink disease soil pathogen Phytophtora cinnamomi on photosynthesis. Results indicate an increase (11 to 35%) in the photosynthetic rate in hybrid plants (Castanea sativa × Castanea crenata) in contrast to the C. sativa plants (decrease of 19%).

First Report of Chestnut Ink Disease by Phytophthora katsurae on Chestnut in Korea.

Since the late 1970s, chestnut (Castanea spp.) has been one of the most commonly cultivated nuts for human consumption in Korea. In 1998, as much as 100,000 t of chestnut seeds were produced from 79,000 ha of plantations for export (2). Most cultivated chestnuts are hybrids of Castanea crenata and C. mollissima that have resulted in 27 cultivars commonly grown in Korea. In 2004, dead trees of two cultivars (Tsukuba and Ginyose) from different locations were found with black ooze emanating from reddish, sunken tissues on the trunks. When the bark was peeled off, a distinct necrotic region was observed on the basal trunk with the discoloration extending up and girdling the trunk. In November 2006, a Phytophthora species was isolated from the necrotic areas with a CARP selective medium (4). Eleven isolates were obtained from three locations: Hadong, Hapcheon, and Youngqwang. The isolates produced numerous homothallic oogonia (34.0 to 46.2 × 21.9 to 26.7 μm) with warty protuberances on the surface. Antheridia were amphigynous with long, funnel-shaped stalks at the base of the oogonia. The formation of papillate, ovoid to obpyriform sporangia (17.0 to 38.9 × 14.6 to 29.2 μm) was induced by cold treatment in filtered (through 25-μm particle retention) creek water or deionized water. Chlamydospores were not observed. Comparison of the rDNA ITS sequence using ITS1/4 (3) showed 99.6% similarity to P. katsurae (GenBank Accession No. AF266771) with three base pair differences. All eleven isolates showed identical ITS sequences. Pathogenicity studies were conducted on excised three 15-cm-long × 5-cm-diameter logs from each of three chestnut cultivars (Moriwase, Parkmi 2, and Ibuki). Bark (5 mm in diameter) was taken with a cork borer on each log followed by inoculation with a 5-mm agar disk of two isolates, PH.K01 and PH.K07. The logs were placed in a moist chamber for 7 days. Noninoculated controls consisted of log sections from each cultivar treated with agar disks. The pathogencity test was repeated three times. The entire log of cv. Parkmi 2 became necrotic, whereas the other two cultivars developed only small lesions (P < 0.0001). The noninoculated control logs of each cultivar did not develop lesions and no pathogen was reisolated from them. This suggests that cultivars differ in susceptibility. P. katsurae (synonym = P. castaneae) was first described from Japan in 1931. P. cambivora, P. cinnamomi, and P. katsurae are commonly responsible for ink disease on chestnut species in Europe, the United States, and Asia (1). The impact of P. katsurae on chestnut production in Korea is currently unknown.

Assessment of the spread of chestnut ink disease using remote sensing and geostatistical methods

Chestnut ink disease, caused by Phytophthora cinnamomi and P. cambivora, is responsible for important economic losses and limits the establishment of new chestnut (Castanea sativa) groves in Portugal. Although the differences in soil properties and in cropping practices affect ink severity, the regional spread of disease is not known. Data for monitoring C. sativa decline were obtained by using field surveys and Small Format Aerial Photography (SFAP), a reliable tool which provides large-scale imagery obtained at low altitude. Visible colour and near-infrared images were obtained with different cameras with an average ground resolution of 22, 14 and 39 cm. The spatial distribution of ink disease in northern Portugal for the years 1995–2004 was estimated through a geostatistical method, and the estimation of precision was determined. From 1995–2002, the chestnut population in the study area increased by 18.5% due to new orchard plantations. After 2002 the population decreased because the new plantations were not sufficient to recover the number of dead chestnut trees, killed mostly by ink disease. The directional semivariograms indicated anisotropy with a greater disease spread in the NE–SW direction. This direction corresponds to site areas at the same altitude, where soil tillage and human mobility are higher.

ASSESSMENT OF CHESTNUT INK DISEASE SPREAD BY GEOSTATISTICAL METHODS

Chestnut ink disease of chestnut associated with the soil-borne pathogen Phytophthora cinnamomi Rands, is observed in single trees as rarefied foliage and general dieback which begins at the branch tips. These conditions can be detected by satellite images with high spatial resolution or by large format aerial photography. However, capturing those images frequently over small sampling areas is very expensive. This study presents an alternative method to evaluate chestnut health using lower cost technology: Small Format Aerial Photography (SFAP), of ground plots taken from light aircrafts. Normal colour and infrared SFAP from 2000 and 2001 were compared with on-the-ground evidence of chestnut ink disease. The spatial variability of health conditions of chestnut plots was adjusted in experimental semivariograms, using a spherical model. The spread of ink disease was then interpolated by ordinary kriging. Different vegetative conditions were detected using SFAP, in 2000 and 2001, showing, respectively, 5.6% and 11.1% of dead chestnut trees. The geostatistical interpolation of the study area (460 ha) found a critical cluster where chestnut decline had increased.

Efficacy of biofungicides Supresivit and Polyversum against Phytophthora root pathogens on European chestnut (Castanea sativa Mill.)

The effect of two commercially produced biopreparations on the originators of chestnut ink disease in Slovakia &amp;ndash; soil fungi Phytophthora cambivora and Phytophthora cinnamomi was tested in laboratory conditions. Investigations of interrelations between Trichoderma harzianum (Pythium oligandrum) and isolates of Phytophthora sp. obtained from infected tissues of Castanea sativa Mill. proved more important inhibitive effects for Pythium oligandrum (biopreparation Polyversum) efficiency 25.3% (Ph. cambivora) and 26.2% (Ph. cinnamomi). Biopreparation Supresivit (Trichoderma harzianum) reached the efficiency 9.1% for Ph. cambivora isolates and 9.2% for Ph. cinnamomi isolates. Significant effect of the used bioformulas for inhibition of mycelial growth of both Phytophthora sp. and significant difference in the efficacy of two different bioformulas were confirmed statistically. &amp;nbsp;

Soil compaction and chestnut ink disease

SummaryChestnut ink disease caused by the oomycete Phytophthora cinnamomi, a soil‐borne pathogen of world‐wide distribution, accounts for the majority of disease problems on chestnuts in Portugal, limiting yield in a large number of stands and impeding establishment of trees in new areas. A survey was carried out in 32 chestnut stands in the Padrela Mountains of northern Portugal to investigate the relationship among ink disease occurrence, edaphic factors and management practices. A logistic regression function was employed to analyze the effect of soil attributes and management practices on the stand health status. Results showed that the main factors affecting disease were soil compaction (COMP), soil organic matter level (OM) and manuring practice (MA). A logistic model containing the soil variable COMP and the interaction term OM × MA correctly predicted the stand health status in 94%, or 30, of the 32 stands studied. The logistic function coefficients indicate that the probability of a stand having ink disease increases with increasing soil compaction and increasing soil organic matter content in stands where manuring is the usual practice.

Effect of Chestnut Ink Disease on Photosynthetic Performance

AbstractIn order to evaluate the evolutionary impact of chestnut ink disease, infected trees (cv. Judia), were compared with non‐infected trees, in three separate months: July, September and October. The aim of this work is to analyse the effects of the infection using parameters related to plant water relations, gas exchange and biometric data of leaves and fruits. In this period, temperatures decreased from 31 to 16°C contrarily to precipitation, which increased from 18 to 178 mm, respectively. In consequence, leaf water potential changed between −1.6 and −1.0 MPa while in infected plants the values maintained around −1.2 MPa over the referred period. Nevertheless, at the gas exchanges level, differences in stomatal conductance, transpiration and photosynthesis were only detected in October. Concerning photosynthesis rate, the infected plants showed, in relation to September, a reduction around 35% whereas in non‐infected plants the decline was 25%. Alterations in the chlorophyll contents were also observed between September and October. In infected plants reduction on total amount of chlorophyll was from 18.6 to 13.4 mg/Wf, while in non‐infected plants values were only decayed from 15.1 to 13.1 mg/Wf. In relation to chlorophyll a/chlorophyll b ratio, plants infected by the oomycete preserved values in the level of 2.6, whereas in healthy plants values changed from 2.5 to 2.3. Leaves and fruits from infected chestnut trees were 13 and 20% smaller, respectively than those from non‐infected. Fruits from infected plants also had less starch but more crude protein.

Soil physical properties and the occurrence of chestnut ink disease : a micromorphological study

Ink disease caused by the fungus Phytophthora cinnamomi Rands is a major threat to the sustainability of chestnut ecosystems in northern Portugal. Not only soil factors and host resistance but also management practices can influence the occurrence of this disease. Total soil porosity was measured in chestnut groves affected by the ink disease and in healthy ones, at 2 or 3 depth zones. The orchards were located either in mid-slope position or at the foot of the slope. The purpose of the work was to investigate whether or not the occurrence of ink disease would be related with the presence of a plough pan and with the topographical position of the stand. The areas covered by pores with Ø&gt;3O µm (po30) and by pores with Ø&gt;5OO µm (po500) were directly quantified on soil thin sections using micromorphological and image analysis techniques. This method was chosen because routine methods fail to detect soil porosity differences in the soils with a clear plough pan. The results show that low absolute total porosity does not directly influence the health status of the orchards. However, the presence of a layer with reduced porosity at 20-35 cm clearly affects the occurrence of ink disease. This plough pan strongly hinders root development and soil aeration and thus makes the trees more sensitive to the attack of Phytophthora cinnamomi. The plough pans observed were more pronounced in the foot-slope than in the mid-slope soils. Former studies have shown that lowland groves are also more intensively affected by ink and that there is a close relationship between the number of tillage operations and the incidence of the disease. This study evidences the relationship between the occurrence of Phytophthora root disease and the presence of a plough pan, which in turn depends on the location of the stand on the slope. From a methodological point of view it stresses the importance of micromorphological and image analysis techniques to directly determine total soil porosity and to provide complementary and more accurate data than the indirect methods commonly used for quantifying soil porosity.

Effect of ectomycorrhizal fungi on chestnut ink disease

Effect of ectomycorrhizal fungi on chestnut ink disease

Effect of ectomycorrhizal fungi on chestnut ink disease

Seedlings of Castanea sativa were inoculated at transplanting time with four ectomycorrhizal (ECM) fungi, Laccaria laccata, Hebeloma crustuliniforme, H. sinapizans and Paxillus involutus. At the end of the first vegetative season, 7 months after sowing, half of the mycorrhizal and nonmycorrhizal seedlings were challenged with a zoospore suspension of Phytophthora cambivora and the other half with P. cinnamomi. Five months later, mycorrhizal plants infected with P. cambivora or P. cinnamomi showed no sign of pathogen infection. The ECM fungi increased plant biomass also in the presence of the pathogen. Mycorrhizal seedlings inoculated with the pathogens showed greater shoot and root development than nonmycorrhizal chestnut plants. All the fungi tested reduced the negative effect of the ink disease pathogens on the plant host in vivo. The mechanisms by which the ECM fungi protect chestnut seedlings are discussed.

ASSESSMENT OF RESISTANCE TO CHESTNUT INK DISEASE

ASSESSMENT OF RESISTANCE TO CHESTNUT INK DISEASE