Trunk Cankers Research Articles

Dispersal gradients of conidia of the butternut canker fungus in a forest during rain

Dispersal gradients of conidia of Sirococcusclavigignenti-juglandacearum Nair, Kostichka, and Kuntz, the causal agent of butternut canker, were studied in the forest for various rainfall dates. During rain, large numbers of conidia from branch cankers were carried in runoff water down the tree trunks of butternut (Juglanscinerea L.), causing infections that resulted in trunk cankers. Conidia also were dispersed in small droplets or aerosols and disseminated up to 40 m from a cankered tree during rainfall. Concentrations of conidia in the air decreased exponentially with increasing distances from the inoculum source. Dispersal gradients were influenced by stand composition and (or) size of the inoculum source, with steeper gradients associated with a dense forest canopy and a small area source of inoculum. Weather conditions, excluding the necessity for rain, had little influence in altering dispersal gradients within the same stand for different rainfall dates.

Zelkova: A 20-Year History in Southern Michigan

In 1955, 102 Zelkova serrata trees were planted on the grounds of the Agricultural Experiment Station at Michigan State University at East Lansing. During the next 10 years, 23 trees died of unknown causes. Beginning in 1966, the condition of each tree was determined annually. By 1975 an additional 38 trees had died, primarily from nectria canker (Nectria cinnabarina) or mouse injury. Death from canker could not be correlated with the frequent injury the trees received from lawnmowers but once a tree became colonized by canker, it usually died. Of the 41 trees alive in 1975, 25 had good or satisfactory crown shape while 16 had distinctly lopsided crowns. None of the 41 trees had active trunk cankers but 6 trees had. at least one active canker on a main branch. Eight trees had severe V-crotches where the trunk divided into the crown. The trees had an average diameter one meter above ground line of 16 cm; the largest being 27 cm. In spite of the rather high mortality of these trees, Zelkova appears to be a suitable shade tree if care is taken in site selection and maintenance.

Canning peach decline in Western Australia. I. Association between trunk cankers, trunk pruning wounds and crotch angles of scaffold limbs

Decline of South African canning peach varieties, particularly commercial plantings of Keimoes, has occurred in Western Australia. From orchard observations and laboratory investigations, it is suggested that tree death follows on canker formation on the trunk. The cankers extend from areas of compressed dead bark between scaffold limbs and from large uncallused pruning wounds in the crotch and on the trunk. Wood-rotting fungi are considered to gain entry through the dead bark and uncallused wounds. Analysis of the data shows a highly significant relationship between many cankers and narrow crotch angles. No correlation has been established between the extent and severity of trunk pitting and the development of cankers.

Phytophthora heveae . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Phytophthora heveae . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Hevea rubber, cacao, Brazil nut, Agathis australis , guava, mango, avocado pear. DISEASE: Pod rot and black stripe of rubber; pod rot of cacao; leaf blight of Brazil nut; avocado pear trunk canker. GEOGRAPHICAL DISTRIBUTION: Asia (Malaysia, India); Australia (Queensland, New South Wales); New Zealand; Papua New Guinea; North America (USA); Central America (Guatemala); South America (Brazil). (CMI Map 428, ed. 1, 1967). TRANSMISSION: Soil-borne. Isolated from forest soils (44, 1944); soil in rubber plantation (49, 2165); in Agathis australis stand (54, 3493); in Eucalyptus plantation (55, 4876).

Virus and Virus-Like Diseases Affecting Grapevines in New York Vineyards

Three grapevine diseases of economic importance that have been identified in New York State are described here. One disease is induced by tomato and tobacco ringspot viruses and causes a decline of grapevines. A second disease is characterized by trunk cankers that enlarge gradually and kill the grapevines. <i>Eutypa armeniacae</i> Hansf. &amp; Carter is always isolated on artificial media from established cankers and is likely the causal agent involved. The third disease with downward curling and yellowing of leaves, delayed ripening of shoots, and shriveling of berries is of limited occurrence and the causal organism is unknown.

Virus and Virus-Like Diseases Affecting Grapevines in New York Vineyards

Three grapevine diseases of economic importance that have been identified in New York State are described here. One disease is induced by tomato and tobacco ringspot viruses and causes a decline of grapevines. A second disease is characterized by trunk cankers that enlarge gradually and kill the grapevines. <i>Eutypa armeniacae</i> Hansf. &amp; Carter is always isolated on artificial media from established cankers and is likely the causal agent involved. The third disease with downward curling and yellowing of leaves, delayed ripening of shoots, and shriveling of berries is of limited occurrence and the causal organism is unknown.

Studies on the trunk canker and death of apricot trees. 1

Studies on the trunk canker and death of apricot trees. 1

Effects of Rootstock on Growth, Bloom, Yield, Maturity, and Fruit Quality of Prune (Prunus domestica L.)1

Abstract Tests in 11 plots of ‘Italian’, ‘Early Italian’, and ‘Brooks’ prunes showed several influences of rootstock on tree growth, flowering, yield, fruit size, maturity, and quality. Of the 6 Prunus species represented by the 19 rootstocks tested, myrobalan roots usually resulted in larger trees, heavier bloom, but lower yield efficiency than did peach roots. Trees on Marianna and several P. domestica L. roots varied in size and yield, but most of them had greater bloom density than trees on peach root. ‘Italian’ fruit firmness varied inconsistently with rootstock. ‘Early Italian’ fruits were firmer on peach than on other roots, but ‘Brooks’ fruits were less firm on peach than on other roots. The tendency for internal fruit browning of ‘Italian’ was greater on plums than on peach roots. Other fruit maturity and quality factors varied by cultivar and by individual rootstock. Fewer trees on peach root died from trunk canker (Pseudomonas syringae van Hall) than did those on several clonal plum roots, but some plum-rooted trees outgrew the canker and survived as well as trees on peach stock.

Phomopsis conorum (Sacc.) died.—An old fungus of the Douglas fir and other conifers

Summary Phomopsis conorum on the shoots of Douglas fir (Pseudotsuga Douglasii) is recorded for the first time from Great Britain. Unless a critical examination is made this Phomopsis may be easily confused with Phomopsis Pseudotsugae to which the Phomopsis disease of Douglas fir and other conifers has been previously attributed. A Phomopsis sp. has also been discovered among the herbarium specimens on various conifers, identified by Rostrup as Phoma pitya Sacc., which bears a strong morphological resemblance to Phomopsis conorum from Great Britain. The type of Phoma pitya Sacc. has been examined and proves to be a typical Sclerophoma (S. Magnusiana). A full description of Phomopsis conorum is given based on fresh material of Douglas fir from Scotland. Fresh collections of the fungus are also reported from Wales and England, Holland, and Denmark. Picea, Pinus and Abies are other hosts for the organism. P. conorum differs from P. Pseudotsugae both morphologically and physiologically. There are distinct cultural differences. Preliminary inoculation experiments with P. conorum indicate it to be only a saprophyte, while inoculation experiments with P. Pseudotsugae have shown it to be a true parasite. P. conorum has not been observed associated with a definite branch and trunk canker of the Douglas fir, such as is reported for P. Pseudotsugae.