The Una-Sana Canton (the northwest part of Bosnia and Herzegovina) abounds in large forest areas, where the self-sown sweet chestnuts Castanea sativa Mill. grow. However, the plant has been endangered due to the negative effects of disease-causing agents, harmful insects, and human factors (uncontrolled forest logging). Moreover, the chestnut weevil Curculio elephas causes significant damage to the local chestnut fruit. This study aims to analyze the emergence of the pest and the damage which it produces in the forest areas of the northwestern Bosnia and Herzegovina, precisely in Una-Sana Canton. The presence of the chestnut weevil has been examined on samples taken from 15 locations in chestnut forest in the municipalities of Cazin, Velika Kladuša and Bužim. In order to research this phenomenon more precisely, each fruit has been cut, the larvae have been separated from it and damage in the inner part of the fruit has been observed. The number of larvae has been noted per a sample. With respect to each sample, the mass of healthy and damaged part of the fruit has been measured. The number of larvae ranges from 5 to 15 per sample. The percentage of damaged fruit parts ranges from 4,2% to 13,6%. The reason for the increased presence of the chestnut weevil in the analyzed chestnut forest is in addition to the beneficial chemical composition of the fruit and the late detection of the presence of insect existing in severely large populations. The use of chemical preparations (pesticides) as a solution to this issue is ecologically unacceptable, especially in a larger area. It is mandatory to manually collect all the fruit that fells of the chestnut trees prematurely and, moreover, to stop the further development of the larvae. Considerable results can also be achieved by separating individual chestnut stands and changing the purpose of its use, as well as combining the method with the limited use of pesticides.

In 2015, wheat fields on the territory of Una-Sana Canton (northwestern Bosnia) were regularly inspected. Occurrence of Gaeumannomyces graminis (Sacc.) von Arx et Olivier (syn. Ophiobolus graminis Sacc.) was registered in a large number of localities. In vegetation period, symptoms characteristic for this fungus were observed on spike and roots. The fungus G. graminis was isolated from a large number of collected wheat samples which were analyzed in the laboratory by the conventional method. In 2015, presence of the pathogen was registered on 12.8% of the wheat acreage. Infection intensity above 15 was registered on 16 % of the infected acreage and 2% of the total wheat aceage. After harvest, infected wheat grains were measured for absolute and hectoliter weights, which were found to range from 26 to 40 g and from 63 to 68 kg, respectively. To improve the effectiveness of crop protection, it is necessary to apply the required agricultural practices (long-term crop rotation, control of volunteer wheat and grassy weeds, plowing under of harvest residues, balanced fertilization) and treat wheat seed with fungicides from the groups of benzimidazoles, triazoles and triadimenoles. Biological protection is possible with bacteria Pseudomonas fluorescens and fungi Trichoderma viridis.

In 2010. and 2011, barley fields on the territory of Una-Sana Canton (northwestern Bosnia) were regularly inspected. In addition to the common diseases, occurrence of Rhynchosporiumsecalis (Oudem.) J. Davis, (Syn. Rhynchosporium graminicola Heinsen) was registered in a large number of localities. The typical symptoms were visible on the leaves, the smaller of the branches of leaf. On the reverse of leaves emerged gray-white coating, composed of konidiofora and the conidia. The fungus R. secalis was detected on a large number of collected barley samples which were analyzed in the laboratory by the conventional method. In 2010, infection symptoms were found at 70% of the barley acreage, in 2011. at 55% of the acreage. The intensity of infection higher than 70% was registered in 20.9% of the infected acreage for winter barley, and 18.3% for spring. The computed severity coefficients of noxiousness ranged from 28 to 59. The lowest coefficient was established for the cultivar Matej, the highest for the cultivar Novosadski 313. After harvest, infected barley grains were measured for absolute and hectoliter weights, which were found to range from 25 to 43 g and from 51 to 63 kg respectively. To improve the effectiveness of crop protection, it is necessary to apply the required agricultural practices: long-term crop rotation, control of wild barley and grassy weeds, plowing under of harvest residues, balanced fertilizzation and treat barley with fungicides from the groups of karbendazimes, propikonazoles and triadimefonales.

The cause for the common bunt of wheat, Tilletia tritici (Bjerk) Wint. in Rabenh., sin. Tilletia caries (DC) Tul&Tul was researched during 2001, 2002, 2003 on the territory of Una-Sana Canton (Bosnia&Herzegovina). In the stage of milky ripeness, a detailed examination of plants was undertaken on many localities and symptoms typical for T. tritici were detected. On several occasions, an infection intensity determined by counting sickly ears on m2 was determined. A resistance of sorts was determined according to scale 0-IV, and after the harvest, the presence of teleutspores on the seed of wheat was analyzed. High intensity infection was present in Cazin and Bihac municipalities. The sort Bosanka was resistant to infection during all three research years. Sorts Granada and Fortuna showed middle resistance while other sorts were mainly middle sensitive. In 2001, 51 samples of wheat seed were analyzed and with 34 samples, there was the presence of teleutospores detected. In 2002, 53 samples were analyzed and the presence of teleutospores was found with 25 samples. In 2003, 50 samples were analyzed and 20 of them were infected with T. tritici. The main cause for the intensified occurrence of T. tritici at this area is sowing of an undeclared seed, sowing of a seed from home production, then a harvest of a healthy seed contaminated by combine-harvester. It is necessary to educate farmers about hazardous effects, expansion and protection measures, as well as not implementation of agricultural measures in terms of Tilletia ssp., identification of the pathotypes and introduction of resistant sorts. .

Growth retardation at early growth stage and chlorosis typical for P deficiency has been found in maize plants grown on some soils in the northern Bosnia. As chlorotic and normal plants grown on same plots, comparative analyses of chemical composition of aerial part of maize were made. In these preliminary investigations dry matter yield and P concentration of chlorotic plants were very significantly lower, while the Al and Fe concentration were higher as compared to non-chlorotic plants. Mainly low status of mobile P was found by soil testing. As affected by liming of Brcko state farm soil, yield of wheat was significantly increased 0.3 t/ha or 5% only, while yield of maize was similar to the control, although of improved P status in plants (ear-leaf of maize and flag-leaf of wheat). Low or absence effects of liming in USA were found mainly when low pH is not accompanied with high levels of mobile Al and Fe in soil. Under influences of P fertilization in Knespolje area, maize yields were increased up to 32% and 17% compared to the control, for 2004 and 2005, respectively. Also, there were tendency for increases protein and oil contents.

The results of a two-years investigation of the efficacy of fungicides used for seed treatments of the winter wheat variety Zlatka against T. tritici are presented. The following fungicides designed for seed disinfection were used: Dividend 030 FS, Vitavax 200 FF, Raxil 060 FS, Panoctine 350 IS. All of the tested fungicides were found to be highly effective, the top efficacy being archived by Dividend 030 FS, followed by Vitavax 200 FF (99.99%), Raxil 060 FS (99.98%), and Panoctine 350 (99.96%). Such high efficacy shows that it would be desirable to increase the use of these wheat seed disinfectants in North-Western Bosnia. Wheat yields were found to increase 15.5 - 26.3% in 2003 and 15.6 - 28.9% in 2004, compared to control. The differences in yields, in relation to control, were statistically significant, while the effect of fungicide treatments on weight per thousand kernels and hectolitre mass of seeds was not statistically significant.

In 2002 and 2003, wheat fields on the territory of Una-Sana Canton (northwestern Bosnia) were regularly inspected. In addition to the common diseases (powdery mildew, leaf rust, septoria), occurrence of Gaeumannomyces graminis (Sacc.) von Arx et Olivier (syn. Ophiobolus graminis Sacc.) was registered in a large number of localities. Symptoms of the disease could be observed at the stage of milk maturity and beginning of wax maturity. The infected spikes were white, empty, with a small number of poorly filled grains. Microscopy observations of the roots showed In object reinstatement diagnosis was examined root and under microscope was espied fibrous stuff long some mm were established on exterior and interior mycelia. The consequent tissue necrosis and root rot created conditions favorable for the attack of parasites causing "black spikes". The fungus G. graminis was isolated from a large number of collected wheat samples which were analyzed in the laboratory by the conventional method. In 2002, infection symptoms were found at 35% of the wheat acreage, in 2003 at 32% of the acreage. Infection intensity above 15 was registered at 8-10% of the infected acreage. The computed severity coefficients of noxiousness ranged from 10 to 35. The lowest coefficient was established for the cultivar Bosanka, the highest for the cultivar Marija. After harvest, infected wheat grains were measured for absolute and hectoliter weights, which were found to range from 25 to 30 g and from 60 to 70 kg, respectively. To improve the effectiveness of crop protection, it is necessary to apply the required agricultural practices (long-term crop rotation, control of volunteer wheat and grassy weeds, plowing under of harvest residues, balanced fertilization) and treat wheat seed with fungicides from the groups of benzimidazoles, triazoles and triadimenoles.