Tomato stand-alone or multiple-bay greenhouses is on the increase, providing fruit during those times of the year when field-grown fruit is not readily available. Smaller sized fruit (cherry and grape), or cluster tomatoes (fruit-on-the-vine) are the fruit of choice for the large commercial greenhouse operators while the beefsteak varieties are the choice of owner-operator growers. Hydroponic technique is often used in hostile growing environments, as well as high-density plantings. To facilitate transportation and storage, tomatoes are often picked unripe (green) and ripened in storage with ethylene. Unripe tomatoes are firm. As they ripen they soften until reaching the ripe state where
Plum pox of stone fruit by causing acidity and deformities. The only way to manage the disease is to destroy all infected trees, which can cause significant economic losses. The disease symptoms were first seen in Bulgaria around 1916-1917, thus the name of "sharka" - from Bulgarian "шарка", meaning "pox". In 1933, the virus origin was described by Dimitar Atanasov. The disease developed in several European countries. The plum pox virus is a linear single stranded RNA virus. There are nine strains of plum pox virus: PPV-D, PPV-M, PPV-EA, PPV-C, PPV-Rec (Recombinant), PPV-W, PPV-T, PPV-CR, and PPV-An. PPV-M isolates are more aggressive