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  • Author or Editor: James D. McCreight x
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Abstract

Greenhouse and field tests showed casaba melon, (Cucumis melo L. cv. Deserta Naja) to be highly susceptible to the western spotted cucumber beetle (Diabrotica undecimpunctata ssp. undecimpunctata Mannerheim). F1 and F2 progenies derived from a cross between ‘Deserta Naja’ and a comparatively resistant melon aphid-resistant breeding line ‘Top-Mark’ were nearly as susceptible as ‘Deserta Naja’, indicating a dominance of susceptibility. The mean damage to the progeny was significantly different from that of ‘Deserta Naja’; however, this indicated that dominance was incomplete. Greater numbers of the beetles on ‘Deserta Naja’ than on other entries in a field trial indicated that preference is associated with its high susceptibility. Differential damage to ‘Top-Mark’ in free-choice and no-choice tests supported the theory that resistance includes non-preference.

Open Access

Three races of Fusarium oxysporum f.sp. lactucae, cause of fusarium wilt of lettuce, are known in Japan, where the pathogen was first observed in 1955. Fusarium wilt first affected commercial U.S. lettuce production in 1990 in Huron, Calif., but did not become a serious problem in the U.S. until 2001 when it reappeared in Huron and appeared in the Yuma, Arizona lettuce production area. Reactions of three fusarium wilt differentials (`Patriot', susceptible to races 1, 2 and 3; `Costa Rica No. 4', resistant to race 1, and susceptible to races 2 and 3; and `Banchu Red Fire', susceptible to races 1 and 3, and resistant to race 2) in a naturally-infected commercial field test and artificially-inoculated greenhouse tests, indicated presence of race 1 in the Yuma lettuce production area. Reactions of these differentials to an isolate from Huron confirmed the presence of race 1 in that area. Consistent with previous results from the U.S. and Japan, `Salinas' and `Salinas 88' were resistant to the Yuma and Huron isolates of race 1, whereas `Vanguard' was highly susceptible. Limited F1 and F2 data indicate that resistance to race 1 in `Costa Rica No. 4' and `Salinas' is recessive. `Calmar' is the likely source of resistance in `Salinas' and `Salinas 88'.

Free access

Fruits and seeds of cucumber (Cucumis sativus L.), melon (Cucumis melo L.), 11 other cucurbit species and five non-cucurbit species were collected in the states of Rajasthan, Madhya Pradesh, and Uttar Pradesh in October and November, 1992. Seeds were collected from cultivated and noncultivated areas, vegetable markets (subji mundi), and from seed dealers. Though many samples were collected as fruit, we were not always able to observe the plants or the growing areas. The origin, description, and use of the collections were noted at the collection site whenever possible. Cucumber landraces were scarce whereas melon landraces were abundant. Of the 681 collections, there were approximately 186 cucumbers and 447 melons. Exact numbers will be known after discrepancies in the records have been resolved. These seeds will be available after they have been increased and documented in the U.S. Germplasm Resources Information Network (GRIN) database. To that end, 1993 plans call for increase, and morphological and biochemical evaluations of a significant portion of the cucumber and melon collections in the U.S., and a substantial parallel increase and morphological evaluation of the collections in India.

Free access

Cucurbit powdery mildew (CPM) caused by Podosphaera xanthii (Px) is an economically important disease of bitter gourd (BG; Momordica charantia) in Asia. High-level resistance to CPM is known in various BG accessions that have been used to develop BG breeding lines that originated in different countries. BG breeding lines THMC 113 (Belize), THMC 143 (India), THMC 153 (Thailand), THMC 167 (India), and THMC 170 (Taiwan) possess high-level resistance to BG Px race (BG-CPM), designated Mc-1 from a field at Kamphaeng Saen, Thailand, whereas THMC 144 (India) is susceptible. Our objective was to determine the inheritance of resistance to BG-CPM race Mc-1. To that end, THMC 144 (India) was crossed with the five resistant lines. The parents and their respective F1, F2, backcross progenies were evaluated for BG-CPM disease severity in inoculated field and growth chamber tests. Resistance to BG-CPM race Mc-1 in the five resistant lines was controlled by at least two independent, recessive genes. Intercrosses of the BG-CPM–resistant lines revealed allelic resistances in four of the breeding lines: THMC 113, THMC 153, THMC 167, and THMC 170. Resistance in THMC 143 was clearly non-allelic for resistance to BG-CPM with the other four BG-CPM–resistant lines.

Free access

Bitter gourd (Momordica charantia L.) is a commercially and nutritionally important market vegetable in Asia cultivated mainly by smallholder farmers. Cucurbit powdery mildew (CPM) caused by Podosphaera xanthii (Px) is a nearly ubiquitous and serious fungal disease of bitter gourd. Five bitter gourd breeding lines (THMC 113, THMC 143, THMC 153, THMC 167, and THMC 170) were selected at the World Vegetable Center for resistance to a local isolate of Px in Kamphaeng Saen, Thailand. We evaluated the resistance potential of these five inbred lines against local isolates of Px at 12 locations in five Asian countries. Plants were inoculated with the respective local Px isolate 15 and 30 days after transplanting and additional Px-infected plants of the inoculated control were interplanted throughout each test. Plants were rated 60 days after transplanting for CPM reaction using a 0 (no evidence of infection) to 5 (>75% infection evident on individual leaves) disease severity scale. THMC 153 and THMC 167 were resistant to the local race of Px in all locations, whereas THMC 143 was observed resistant in all test locations except one in China. THMC 113 was resistant in each location except one in India. THMC 170 was susceptible in three locations in India. The multilocation tests revealed four unique Px races on bitter gourd in different Asian countries and sources of resistance for breeding CPM-resistant bitter gourd cultivars. Six strains of Px isolated from other cucurbits (Cucumis and Cucurbita) and representing five melon CPM races were unable to infect the susceptible M. charantia accession THMC 144 and the five resistant breeding lines, indicating pathotype differences between them and an isolate of M. charantia origin typed as race 1 on melon. THMC 143 and THMC 167, which originated from India, exhibited good yield potential in trials conducted in Thailand, Myanmar, Vietnam, and Bangladesh.

Free access