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 Plum pox Plum pox, also known as sharka, is the most devastating viral disease of stone fruit from the genus "Prunus". The disease is caused by the plum pox virus (PPV), and the different strains may infect a variety of stone fruit species including peaches, apricots, plums, nectarine, almonds, and sweet and tart cherries. Wild and ornamental species of "Prunus" may also become infected by some strains of the virus. The virus is transmitted by aphids and by the transfer of infected plant material to new locations. Plum pox poses no danger to consumers, but it can ruin the marketability