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    Magnesium deficiency on tomato

    A typical case of magnesium deficiency in tomato plants, in a field in the region of Kavala, N. Greece. Interveinal chlorosis on old/mature leaves at the base of the plant is evident. Application of a foliar magnesium fertilizer was recommended to correct the condition quickly and avoid severe impact on the quality and quantity of production.

    Usually magnesium deficiency occurs in soils with a low content of magnesium and in light and acidic soils in which magnesium is easily leached. In soils with a pH from 4.5-5.0, any addition of magnesium to the soil leads to excessive and rapid leaching of the element. In these cases, use of dolomite is recommended for the simultaneous rise of pH and administration of magnesium. Application of magnesium sulfate or magnesium oxide to the soil can also correct the shortage of magnesium when pH is elevated.

    Shortage of magnesium can also occur in soils with high salinity and where large quantities of manure or fertilizers rich in potassium have been used. Finally, it can occur in soils with nutrient imbalance caused by excessive administration of potassium or calcium.

    Author/photos: Aris Chloridis

    Zinc deficiency on walnut

    A case of severe zinc deficiency on a walnut orchard in the area of Kavala in N. Greece. The deficiency already caused necrosis and fall of a large percentage of the foliage which is expected to induce quantitative and qualitative loss in walnut production.

    Usually zinc deficiency appears in acidic and zinc-poor soils, in light soils which are poor in organic matter, in calcareous soils which cause drop of zinc solubility in the soil solution and in cases where phosphorus fertilizers were used in excess.

    Author/photos: Aris Chloridis

    Olive peacock spot or olive scab

    A very common and serious disease of olive in Greece, which causes weakening of olive trees and production decline due to the loss of foliage and therefore inadequate nutrition of trees. In cases of intense infection it can even eliminate production. Cause of the disease is the fungus Spilocaea oleagina. Infection by the fungus is favored by wet weather and medium temperatures, therefore it is more intense from spring to start of summer and in autumn. The disease is controlled mainly with the use of copper compounds.

    Author/photos: Aris Chloridis

    Grapevine Downy Mildew

    From a visit to a new vineyard (variety Jack’s Salute) of a farmer/partner of Agrocure in Kavala, Greece. The vineyard had quite intensive infection by Plasmopara viticola one of the most important grapevine diseases across the globe. Instructions were given to the farmer for the control of the disease although the current hot and dry weather conditions (end of July) will limit the spread of the disease.

    Text/photos: Aris Chloridis

    Rose black spot disease

    The cause of this well known and widespread disease of the roses is the fungus Diplocarpon rosae (Marssonina rosae). It is the most common and serious disease of rose. The fungus infects the leaves in the spring as it is favored by the spring dew, rain and moisture on the leaf surface. By contrast the high temperatures of June, July and August stop the growth of the fungus. Small brown-black rounded spots appear on the top surface of the leaves which expand gradually.

    Affected leaves may turn yellow and fall eventually, a phenomenon which starts from the old leaves of the plant base. In some cases, the spots remain small and the leaves do not fall. Another symptom may be the appearance of small purple-black spots on tender shoots. Severely affected plants may lose most of their foliage and remain stunted and vulnerable to other adverse conditions.

    Common control measures:

    1. Remove and destroy infected leaves and shoots. Also, remove all infected fallen foliage
    2. Keep foliage dry therefore do not water with sprinkler
    3. Use of fungicides: chlorothalonil, copper fungicides, difenoconazole, mancozeb, penconazole, potassium phosphonate, prochloraz, sulphur, thiophanate methyl, ziram.

    Bitter Pit in an apple storing facility

    Bitter Pit on Granny Smith apples. Bitter Pit is a physiological disorder of apples which most of the times appears post-harvest, during apple storage in cool rooms. Calcium deficiency and calcium/potassium imbalance are the main causes of this condition.

    The problem can get worse in cases of excessive Nitrogen or Potassium fertilization or if Boron is in short supply. Also excessive pruning and thinning lead to big-sized fruits which are more prone to the Bitter Pit condition.

    Visit of AgroCure to a pear farm in Imathia, N. Greece

    The insect which is shown in the photographs is “Cleonos” as called by farmers. This small beetle of the family Curculionidae seems to belong to the species Polydrusus sericeus (or P. formosus).

    Adults of P. sericeus cause extensive damage to buds, tender young leaves, flowers and small fruits of many fruit trees such as apples, pears, cherries, peaches and nectarines. The length of the adults can reach 6-7mm while their color is metallic bright green due to the emerald scales which cover their bodies. Under the scales the body color is dark brown and blackish.

    Adults are active from April to August. They oviposit on bark or leaves of their hosts. Their larvae, 7mm in length, are root feeders.

    Visit to Crocus sativus fields in Kozani, N. Greece

    Visit to Crocus sativus fields in Kozani, N. Greece.

    For those who are not familiar with the biological cycle of crocus (Crocus sativus – Iridaceae), after the collection of flowers and stamens from mid to late October, plants continue their vegetative development, produce new bulbs and enter dormancy in late spring when the vegetation above ground dries.

    A new biological cycle of the plant starts at the beginning of autumn: bulbs re-germinate and new flowers and vegetation appear. The cultivation remains in the field about six years and then crop rotation usually with cereals follows for many years for soil rejuvenation and nutrient replenishment.

    In a recent visit to the region of Kozani, after complaints from farmers and on the spot observation in many fields, it was found that saffron farming suffers from a “degeneration” which becomes intense from the 2nd-3rd year of cultivation. In some fields there are “bald” areas where the plants have been destroyed while in many other fields the vegetation is stunted and the foliage has a bright red-yellow discoloration.

    Many soil fungi have been reported in the relevant literature which can impact saffron cultivation. One of these pathogens which is most likely responsible for the gradual degeneration and elimination of crocus plants is the fungus Rhizoctonia crocorum which has been identified in the past and was incriminated as the cause for loss of plants in the region of Kozani. Since saffron will go to dormancy soon, Agrocure will follow the phenomenon closely from the next growing season