Vegetative rescue potential of Brazil nut through epicormic shoots on detached branches

ABSTRACT Obtaining juvenile material may favor the clonal propagation of Brazil nut, Bertholletia excelsa. We aimed to assess the emission of epicormic shoots on detached branches of Brazil nut trees as a function of the mother tree and branch diameter, in order to provide juvenile material for use in clonal multiplication. The experimental design was completely randomized in a 6 (mother trees) x 3 (stem diameter: < 20 20-40 and 40-80 mm) factorial design, with four replicates. Every five days the number of shoots emitted was counted and the sprouting speed index and average sprouting time were calculated. The number of epicormic shoots and the sprouting speed index were dependent on the interaction between mother tree and branch diameter. Branches with larger diameter (20-40 and 40-80 mm) showed higher potential for obtaining propagules for use in Brazil nut clonal multiplication (cutting, grafting and in vitro cultivation).

In vitro ESTABLISHMENT OF eucalyptus AND corymbia SPECIES FROM EPICORMIC SHOOTS

ABSTRACT The importance of Eucalyptus and Corymbia has been evident in forestry programs, mainly due to their adaptation to various environmental conditions and the multiple products that can be obtained. As the selection and cloning of superior individuals are usually performed in adulthood, the development and adaptation of the vegetative propagation techniques that enable the rescue and in vitro establishment of species are necessary. Thus, the present study aimed to induce epicormic shoots from pruned branches of adult trees and to promote the in vitro establishment of nine species: six of Eucalyptus and three of Corymbia. The material used to obtain the explants came from the selection of two 44-year-old mother plants of each species, from species, and provenance tests. The number of buds and shoots of each branch was evaluated at 15, 25, 35, and 45 days after the beginning of the experiment in a greenhouse. According to the results, the induction of epicormic shoots from pruned branches was considered a viable and efficient technique to obtain propagule sources from adult mother plants of all species, presenting a gradual increase in the evaluated characteristics over time. Also, in vitro culture is an effective alternative to improve the propagation of the evaluated species, with an establishment of up to 62.5%. However, for Corymbia citriodora (Hook.) K.D. Hill & L.A.S Johnson and Eucalyptus tereticornis Smith it is necessary to develop further studies to enable the in vitro establishment.

Situation and perspectives of European ash (Fraxinus spp.) in Ukraine: focus on eastern border

The health condition of European ash (Fraxinus excelsior) stands in Ukraine has become worse since 2006. Firstly, in 2011 an alien invasive pathogenic fungus Hymenoscyphus fraxineus was identified in the eastern part of the country and, subsequently, its presence was confirmed in the western and central parts. The aims of our research were to evaluate the health of ash trees and identify the main causes of ash decline in different regions of Ukraine with emphasis on ash dieback and its association with collar rots. Results showed that since 2013 the number of trees with ash dieback symptoms has been gradually increasing, reaching up to 92 % in 2018. Total mortality due to ash dieback was up to 9 % in 2018. Disease intensity remains high in northern and central Ukraine comparing with the east. Branch dieback, collar rots, epicormic shoots and bacterial disease of ash occurred more often in the eastern region, some symptoms were observed simultaneously. Ash bark beetle galleries, as well as foliage browsing insects, were found mostly in weakened and/or dying trees. It was indicated that collar rots significantly increase the mortality of ash trees. Armillaria spp. fungi were found to be frequently associated with ash dieback on living stems and fallen trees in 2017, causing high rates of mortality in the northern and central regions. For further ash conservation and breeding programmes, resistant trees in severely damaged regions should be selected to preserve genetic diversity in ash populations. Keywords: Fraxinus excelsior, ash dieback, collar rot, bacterial disease, epicormic shoots, Hymenoscyphus fraxineus, Armillaria spp.

Health condition parameters for deciduous trees in the forest stands of Trostyanetske Forest Enterprise

The aim of research was to evaluate the variability and relations with forest health condition its main parameters (defoliation, dieback and epicormic shoots occurrence) in seven tree species: Norway maple (Acer platanoides L.), black alder (Alnus glutinosa L.), silver birch (Betula pendula Roth.), European ash (Fraxinus excelsior L.), English oak (Quercus robur L.), small-leaved lime (Tilia cordata Mill.), and white elm (Ulmus laevis Pall). Research was carried out in 2018 in Trostyanetske Forest Enterprise (Left-bank Forest Steppe; Sumy region). Diameter (DBH), Kraft class, and category of health condition were assessed for each tree. Defoliation, dieback and epicormic shoots occurrence were evaluated as proportion of trees with respective symptoms. Severity of each parameter of tree health condition was estimated using respective scores. No tree species is defoliated over 50%. A birch is characterized by the lowest health condition index (1.6) for living trees, dieback (10%), epicormic shoots occurrence (15.9%) and recently died trees proportion (0.7%), but high proportion of trees died over year ago (10.7%). An oak is characterized by the highest health condition index (2.1), proportion of trees with dieback (45.4%) and epicormic shoots (21.7%). Proportion of trees with dieback is 21.5 to 25% for alder, lime and maple, a bit higher for elm and ash (30.9 and 31.3% respectively). DBH, Kraft class, and health condition index significantly correlate with health condition parameters of analyzed tree species, but the most of correlations are very slight and slight. Correlation between health condition index and defoliation score is significant, positive and high for all tree species (from 0.78 for alder to 0.9 for birch). Correlation between health condition index and dieback score is positive and significant for all tree species, is slight for ash, birch, lime, and alder, and moderate for maple, oak and elm. Correlation between health condition index and epicormic shoots occurrence is significant and positive for all tree species except birch, but is very slight in all cases except elm, where it is slight.

Contribution to the Knowledge of Incidence, Development and Galls of the Bisexual Generation of Biorhiza pallida (Hymenoptera: Cynipidae)

The research study deals with the occurrence, cecidogenesis and development of the bisexual generation of Biorhiza pallida in the Brno region. Galls were found most frequently on Quercus petraea and on Q. robur. At the end of the winter season, females deposited 2–290 (on average 83.6) eggs, mainly into the above average sized buds on last‑year’s shoots. Larvae came to age in May in the 3rd instar, in the extremely warm and dry growing period of 2015 already in the 2nd instar. Adult individuals were leaving galls from the end of May to the end of July. Females were 3–4.5 – times superior to males in numbers. Females, males and individuals of both sexes emerged from 64.3%, 21.4% and 14.3% of galls, respectively. Galls were created from the beginning of April. In the second half of April (or at the beginning of May) they were 3–35 (on average 15.2) mm high and 3–45 (on average 20.2) mm wide. The percentage of buds infestation, average number of deposited eggs and average size of galls were increasing with the increasing mean diameter of shoots. Parasitoids (incl. parasitoid inquilines) killed 30–100 (on average 65) percent of gall wasp population. We found as many as 40% and 10% of galls with the developing Curculio villosus (Curculionidae) and Synergus spp. (Cynipidae), respectively. In the spring of 2016, nearly the whole gall wasp population in Brno‑Komín was killed by late frosts. The pest infests mid‑aged woody plants, sporadically also young growths and epicormic shoots of old oak trees.

EUROPEAN ASH HEALTH CONDITION IN THE FOREST-STEPPE PART OF SUMY REGION

Average health condition index of European ash (Fraxinus excelsior L.) in inspected stands of the State Enterprise “Trostyanetske Forest Economy” is 2 points. European ash mortality was the highest in Krasnyanske forestry (0.8 % and 3.5 % of recently died trees and the trees died over a year ago respectively). The highest proportion of healthy European ash trees were inspected in Makivske and Krasnyanske forestries (85.3 % and 50.1 % respectively). The trees of European ash of the 1st category of health condition can be reliably distinguished from the trees of other categories of health condition. A total score of “0” for all parameters of health condition (defoliation, dieback, and epicormic shoots occurrence) reliably points the healthy tree. The trees can be assigned to the 1st category of health condition with defoliation, caused by insects, up to 50 %, with up to 10 % dry branches and single epicormic shoots. Multiple epicormic shoots are characteristic for the trees of the 3rd category of health condition. Ambiguous results in distinguishing of European ash trees of the 2nd and the 3rd, the 3rd and the 4th categories of health condition confirm the need for improvement of its assessment and annual monitoring the forest health at key plots.

ADVENTITIOUS ROOTING COMPETENCE AND RESCUE OF ADULT MATE PLANTS BY CUTTINGS

ABSTRACT The competence of adult plants of mate (Ilex paraguariensis St. Hil.) to undergo adventitious rooting is essential to their vegetative rescue by cuttings. This study aimed to evaluate the adventitious rooting competence of adult mate plants, and then rescue these plants by making cuttings from epicormic shoots induced in different trunk positions. The percent survival and rooting of cuttings from epicormic shoots induced by girdling in seven adult plants were evaluated. The two stock plants whose cuttings had the highest rooting competence were further pruned and girdled to evaluate the effect of the position of epicormic shoots on their adventitious rooting competence. The potential success of rescuing of the same adult plants was also studied with cuttings of epicormic shoots induced by coppicing. The shoots were sectioned in single-bud cuttings, either treated with 3,000 mg L-1 indolebutyric acid or untreated, and then cultivated in a humid chamber for 60 days, and then the percent survival and rooting of cuttings was evaluated. In conclusion, we found that it is possible to rescue adult mate plants by cuttings from epicormic shoots induced by pruning, girdling, or coppicing. The adventitious rooting competence of cuttings differs among adult mate plants, and depends on the position of the epicormic shoots on the trunk from which epicormic shoots are collected.

Vegetative rescue and ex vitro system production of Tibouchina sellowiana clonal plants by cutting and mini-cutting

ABSTRACT: We aimed to evaluate the rooting potential of Tibouchina sellowiana through the experiments: I - Cuttings from current-year shoots and epicormic shoots were submitted to IBA concentrations: 0, 500, 1000, 1500 and 2000mg L-1, in a factorial arrangement 2 x 5 (two types of cuttings x five IBA concentrations), with four replicates and 20 cuttings each; II - mini-stumps of Tibouchina sellowiana were submitted to successive shoots collecting during the four seasons, in a split-plot design, with five replications of ten mini-stumps per experimental unit. From the shoots of mini-stumps, mini-cuttings were produced, which were initially kept in greenhouse and later transferred to full sun, in a 4 x 5 factorial arrangement (four seasons x five collections per season), with four replicates of 12 mini-cuttings. Superiority of epicormic shoots cuttings was reported when compared to the current-year shoots, which showed the highest rooting and leaves maintenance (42.50% and 55.00%, respectively), eliminating the use of IBA. High survival of mini-stumps (over 80%) and the mini-cuttings production (170mini-cuttings m-2 month-1) in clonal mini-garden and the mini-cuttings survival (above 80%) in the greenhouse demonstrated the technical feasibility, with summer as the most appropriate time to collect mini-cuttings.

Cuttings of post fire epicormic shoots of Ilex paraguariensis and Cabralea canjerana adult plants

ABSTRACT: The aim of this research was to evaluate the feasibility of rescuing adult plants by cuttings from post-fire epicormic shoots. We evaluated the native tree species erva mate ( Ilex paraguariensis St. Hil.) and canjerana ( Cabralea canjerana Vell. Mart.), which present difficult seedling production and are economically and ecologically important. The plant material used for the preparation of cuttings consisted of shoots from bud differentiation of tissue from the stem collar of the trees. One-bud cuttings of erva mate were treated with 4000 or 8000mg L-1 of indolebutiric acid (IBA) and the checks were not treated with auxins. The cuttings were grown in three different substrates: carbonized rice husks, vermiculite and coarse sand. The experiment was a factorial with a completely random design and five replicates of five cuttings. One-bud cuttings from the basal, intermediate and apical parts of canjerna shoots were treated with 0 or 6000mg L-1 of IBA and planted in commercial substrate and coarse sand (3:2 v/v). The experiment was a factorial with a completely random design and ten replicates of three cuttings. Cuttings from post-fire epicormic shoots can be used for rescuing erva mate and canjerana adult plants. Erva mate cuttings treated with 8000mgL-1 IBA have increased rooting when grown in coarse sand. Canjerana cuttings from the basal part of epicormic shoots have greater survival and rooting than those from intermediate and apical parts.