Phytophthora Crown Rot and Foliar Blight

Phytophthora crown rot and foliar blight, caused by Phytophthora capsici, is devastating to the United States’ winter and summer squash industry. One strategy to control this soil-borne pathogen is to breed for resistance or tolerance. Wild and exotic Cucurbita germplasm provide a valuable source of beneficial genes. The goal of the Cucurbit Breeding & Genetics Program is to evaluate this germplasm for resistance to Floridian isolates of P. capsici. The development of phytophthora resistant breeding lines of summer and winter squash will complement current management practices for the control of P. capsici in squash producing areas.

Squash Silverleaf Disorder

Feeding by the silverleaf whitefly, Bemisia argentifolii Bellows & Perring (formerly known as Bemisia tabaci, Gennadius, B strain) causes a physiological disorder, termed squash silverleaf (SSL) disorder in commercial summer and winter squash varieties. Silverleaf disorder is characterized by a progressive silvering on the upper surface of the leaf due to the separation of the epidermis from the lower cell layers and air space formation within the palisade cell layer. The goal of the Cucurbit Breeding & Genetics Program is to characterize the sources of resistance to SSL disorder in both summer and winter squash. Introgression of the SSL disorder resistance genes into elite breeding lines will be accomplished by generating molecular markers for direct use in marker-assisted-selection.

Powdery Mildew

Powdery mildew caused by Podosphaera xanthii (formerly Sphaerotheca fuliginea) is a major limiting factor in Cucurbita (squash and pumpkin) production in Florida, subtropical and tropical regions of the world. Resistance to powdery mildew has been reported in the wild species C. lundelliana Bailey. The goal of the Cucurbit Breeding & Genetics program is to identify molecular markers linked to this source of resistance to expedite its introgression into elite Cucurbita germplasm through marker-assisted-selection.

Carotenoids

Carotenoids produce pigmentation which results in the range of whites, creams, yellows, and oranges in the flesh color of squash. The expression of this flesh color is conditioned by the particular carotenoid type and concentrations which are influenced by genetic and environmental factors. The goal of the Cucurbit Breeding & Genetics Program is to investigate the various levels of carotenoids present and identify molecular markers associated with these carotenoids within summer and winter squash.