Calag Archive

Powdery mildew is undoubtedly the most widespread disease of roses. The casual fungus, Sphaerotheca pannosa var. rosae, appears as a white or gray powdery or mealy coating on the leaves, tender stems, and flowerbuds. It distorts and discolors those areas, causes defoliation, and reduces plant vigor.

Sweet cherry production in the Sacramento and southern San Joaquin valleys of California has historically been limited by excessive fruit doubling on the commonly grown cultivars. High summer temperatures at the time of flower bud differentiation are generally believed to cause double pistils to form, resulting in many double or spur (one side of the double aborted) fruit at harvest time the following year. Double and spur fruit are considered culls in commercial market channels, and they tend to be more prone to decay than normal cherries.

Few quantitative procedures exist for monitoring lepidopterous pests in processing tomatoes, yet reliable, cost-efficient sampling techniques are essential for the implementation of an integrated pest management program. These sampling techniques must be of such intensity as to predict the amount of damage with a given degree of reliability, yet sufficiently time-efficient to be useful to growers or crop consultants. Without such procedures, assessing a pest's status is subjective and may result in unnecessary control actions. Reliable control decision criteria are especially important in processing tomatoes, where thresholds for damage are set by government or industry standards, and exceeding damage thresholds can result in rejection of the crop.

Deterioration of dried French prunes is characterized by macerated, wet, sticky areas on the fruit surface and by skin that tends to slip with the slightest pressure. This condition is most often the result of fresh-fruit decay caused by the fungus Rhizopus stoioni/er. The mold is also known as “bread mold fungus” or the “whiskers disease” on fresh market stone fruits, strawberries, and almond hulls. Prune growers have called this type of deterioration of dried prunes “box rot” and have suspected it to be responsible for serious losses.