Scots pine (Pinus sylvestris) is Latvia's most economically important tree species. It accounts for 38% of the total forest area of Latvia. One of diseases affecting P. sylvestris is root rot caused by the fungus Heterobasidion annosum, which causes large economic losses. There is some evidence of Scots pine trees with higher levels of resistance but no absolutely resistant tree clones have been described so far. Many genes encoding peptides and proteins with direct or indirect antifungal activity have been described in various plant species, but only few of them have been studied in conifers. In our study we have utilised various approaches to research genetic aspects of Scots pine resistance to H. annosum. Here we present our initial results. Initially, H. annosum infection was determined in 300 trees and in a subset of twenty seven trees representing fifteen families (progeny of one mother tree) infection levels were quantitatively characterised. Candidate-genes were selected based on previously published research. Gene copy number variation (CNV) analyses were performed on selected samples. Copy number variation polymorphism was detected for a gene encoding a thaumatinlike protein analogues of which are described as potent antifungal proteins in other plants. As increased gene copy number can lead to increased gene product amounts in cells it is possible that an increased copy number of thaumatin-like protein is beneficial to the pine tree in respect to resistance against H. annosum and other pathogens. Further experiments need to be performed to investigate this in more detail.

Recent studies have demonstrated the occurrence of different needle cast (Lophodermium spp.) species in young Scots pine Pinus sylvestris L. stands in different regions of Latvia. The impact of these fungi has been known also historically, but is predicted to increase in future due to climate changes that are forecasted to have a positive impact on presence and vigour of various species of fungi. The aim of the study was to characterize the needle cast damage in young Scots pine stands in central Latvia. Material was collected in 12 Scots pine stands at the age of 3 to 26 years in 28 plots with a total area of 8.1 ha in the middle of two consecutive growing seasons (years 2012 and 2013). The impact of disease was visually assessed using a 5 grade scale, depending on the proportion of damaged (brown) one-year old needles. Incidence of damaged trees (P, %) and damage intensity (R, %) was calculated and used to characterize the occurrence and severity of the infection in the stands as well as its link to other stand parameters. Damage incidence (ranging from 20 to 100%), as well as the intensity (from 4 to 35%) was slightly (incidence-also significantly) higher in 2013 in comparison to 2012; correlation between those two parameters was strong in both years (r = 0.94 and r = 0.84, respectively). The stand age, density (ranging from 1200 to 6900 trees haE-1) and tree height did not significantly correlate with the damage incidence or intensity. Forest type (Hylocomiosa or Myrtillosa mel.) was not a significant factor, too.

European pear scab (Venturia pyrina Aderh.) is common and economically important disease in commercial orchards in most of the pear (Pyrus communis L.) growing areas worldwide. Studies on pear scab pathogen V. pyrina diversity in general and among different geographical regions are scars at an early stage. In the limited number of studies reported so far, some attempts have been made to characterize and define races or biotypes of V. pyrina and new biotypes co-adapteted to specific cultivars have been recorded recently. Despite the long history, worldwide distribution and increasing economic significance of the European pear scab, the research on control methods, and pathogen biology and disease epidemiology that could aid to develop more effective and also alternative to fungicide application control methods are still limited. Mechanisms of European pear resistance to scab remains uncertain and currently only one major resistance gene Rvp1 has been identified and characterised. Although the disease is important in many European countries, breeding programs of pear scab-resistant varieties are still under development. In this paper we provide an overview on V. pyrina, its significance and distribution, control methods and current scientific progress in understanding of the pathogen and the disease. Overview of literature on V. pyrina characterization, ecology, biology and diseases epidemiology from Latvia and other countries has been used for the study.

The characteristics of the new potato cyst nematode (Globodera rostochiensis, pathotype RO1) resistant, medium ripening potato variety ‘Teele’ (‘Cinja’ ´ ‘Paola’) developed at the Estonian Crop Research Institute (ECRI) is discussed in this paper. The variety ‘Teele’ was included in Estonian and European Variety List in 2013.The variety ‘Teele’ passed the preliminary, dynamic and final trials in 2008 - 2012 at the ECRI, where it was compared with standard varieties ‘Maret’ (early), ‘Piret’ (medium) and ‘Anti’ (late). The official trials in Estonia and the technical examination (DUS test) in Czech Republic were carried out in 2011 – 2012. Potato cyst nematode (Ro1) and wart (Synchytrium endobioticum (Schilbersky) pathotype 1 (D 1)) resistance of the new variety were determined in Poland in the Plant Breeding and Acclimatization Institute. Tuber yield and tuber weight of the variety ‘Teele’ were equal to ‘Maret’ and ‘Anti’ but higher than ‘Piret’. The number of tubers per plant was equal in all standard varieties. Tuber yield and yield of marketable tubers of dynamic trials present the medium ripening of the variety ‘Teele’. The potato variety ‘Teele’ had good quality characteristics (shallow eyes, regular shape) and good culinary traits of table potato variety. It had a relatively good resistance to late blight (Phytophthora infestans) (field resistance), overcoming standard varieties ‘Maret’ and ‘Piret’.

Breeding work on Ribes species has been started at the National University of Life and Environmental Sciences of Ukraine in Kyiv since 1984 by Petro Sherenhovyj. The breeding programme has been focused on fruit quality, yield, resistance to diseases and pests, as well as on adaptive responses to environmental conditions. As a result of the long-term work, 18 new cultivars were included in the State Register of Plant Varieties of Ukraine in 1999– 2016. The aim of this paper is to describe these varieties: 10 blackcurrant (‘Dochka Vorskly’, ‘Hovtva’, ‘Pam`yati Leonida Mykhalevskoho’, ‘Universytetska’, ‘Aspirantska’, ‘Didorivska’, ‘Poltava 584’, ‘Petrivska’, ‘Yuvileina Sherenhovoho’, and ‘Leleka’), 5 redcurrant (‘Kyianochka’, ‘Poliana Holosiivska’, ‘Buzhanska’, ‘Malva’, and ‘Olha’), 1 whitecurrant (‘Lebidka’), and 2 gooseberry (‘Vasylko’, and ‘Tikych’). The varieties described give farmers and scientists the best knowledge about these cultivars with good level of commercial traits, suitable for dissemination in Ukraine.

Effects of nitrogen fertilizers and weather conditions on spring barley (Hordeum vulgare L.) yield and grain quality were investigated at the Rumokai Experimental Station of the Lithuanian Institute of Agriculture in the period of 1998-2000 and 2003-2004. The soil of the experimental site was Hapli Epihypogleyic Luvisol. Analyses were made with fertilisers rates of 0 and 90 kg haE-1. The data of analyses indicated a positive and reliable correlation between the yield of spring barley and the amount of precipitation in May (rate of correlation was 0.70**) and a negative and reliable correlation with the amount of precipitation in June and July (rates of correlation were -0.80** and -0.29* respectively). A reliable though weak correlation was found between the application of nitrogen fertilisers and the yield of grains. The amount of precipitation in April and the spring barley leaf diseases had a considerable negative effect on 1000 grain weight and grain size. Strong correlation was identified between the amount of precipitation in May and June and the protein content in grain. Nitrogen fertilisers promoted protein accumulation in grain.

Of the citrus diseases occurring in Surinam, fungal, bacterial, viral and those caused by nematodes, tristeza is most important. Trials to identify the best rootstocks to replace the tristeza-susceptible sour orange found Rangpur lime budded with nucellar Alidjan orange best on heavy clay soils. Sunki and King (tangors) are good rootstocks for grapefruit varieties. Research showed tristeza virus transmission by the aphid vector Toxoptera citricidus to be bi-modal (non-persistent and semi-persistent) in Surinam, with the latter more common

The disease is endemic in Guyana and both the B and SFR strains of Pseudomonas solanacearum race 2 are present. Four resistant varieties have been introduced viz. Pilipita, Enano, Congo and Mari Congo, the first of which was best adapted to the conditions but has fruit of limited marketability

Research is directed towards study of host-parasite relations. The 3 Sigatoka leaf spot pathogens, Mycosphaerella musicola (Yellow Sigatoka), M. fijiensis (Black Leaf Streak) and M. fijiensis difformis are compared morphologically and pathogenically. Species identification by electrophoresis on acrylamide gels has been studied, the species also differ in host range, geographical range, symptoms and distribution of lesions. Early tests of susceptibility of plantlets from meristem culture suggest that they react to infection in the same way as observed in the field

The leaf spot diseases of bananas and plantains, Sigatoka and Black Sigatoka, caused by Mycosphaerella musicola and M. fijiensis var. difformis are distributed worldwide and only in Central America respectively. Epidemiological studies are described in detail including seventy of the pathogens at different sites and correlation with climatic data. Susceptibilities of different banana and plantain genomic groups were found to be nearly identical for both diseases except that Black Sigatoka is more virulent so that both pathogens occupy the same ecological niche. A method developed to test the susceptibility of musa clones to Black Sigatoka using plantlets derived from shoot tip culture is described