Cucurbit Genetics Cooperative Report 15:59-61 (article 22) 1992
James D. McCreight
U.S. Department of Agriculture, Agricultural Research SErvice, 1636 East Alisal Street, Salinas, CA 93901
Lettuce infectious yellows (LIY), a sweetpotato whitefly, Bemisia tabaci Genn., (SPWF) transmitted virus disease of melons, has been a problem in fall melon production in the lower desert valleys of California, Arizona and Mexico from 1978 through 1990 (3). In 1990, a new biotype of SPWF was found in these areas. The new biotype, designated the poinsettia (SPWF-P) or IV-90 biotype, differed from the old biotype, designated the cotton (SPWF-C) or IV-81 biotype, by several significant characters including: broader host range, shorter life cycle, i.e. number of days from egg-to-egg, ability to induce silverleaf of squash and inability to transmit LIYV (1, 4, 6). By fall 1991, SPWF-P appeared to have completely replaced SPWF-C (1). In addition, the increased host range, shorter life cycle, and perhaps a favorable environment resulted in unprecedented numbers of SPWF-P that virtually destroyed the Arizona and California fall 1991 melon crop (2) Imperial Valley reportedly suffered $107 million in crop losses to SPWF-P (5).
The initial objective of the present study was to evaluate agrestis type melons for LIYV resistance. The changes in the SPWF population resulted, however, in a virtual absence of LIYV in the fall melons. The large numbers of SPWF and their devastating effect on melon plant growth presented an opportunity to evaluate these melons for resistance to SPWF feeding and reproduction.
A field screening test of 151 agrestis melon PIs was planted at the USDA-ARS, Irrigated Desert Research Station, Brawley on 22 August 1991. Plots were 8.4 m in length on 2 m centers and consisted of 10 hills spaced 76 cm apart; there were two replications. Two seeds were planted per hill; seedlings were thinned to one per hill at the first true leaf stage of growth. LIYV infection was determined by ELISA (3). Plant size and plant condition were evaluated on a plot basis on 22 October; 61 days post-planting.
The PIs were heavily infested with SPWF, plants were stunted, and ELISA samples were negative for LIYV. No data on LIYV resistance were obtained, but preliminary data on resistance to SPWF (Table 1). Melon PIs are known to be variable for many plant characters because the original collection was a mixture, or because of subsequent contamination or cross-pollination during seed increase. For this reason and because these evaluations were done on a plot basis, the mean values presented do not show the true potential of these PIs for resistance to SPWF-P. For example, PI 164825 had a mean rating of 3.5 for size and for condition, but one plant of the 15 plants observed in the two replications was approximately 3-4 times larger than the other PI 164825 plants and was by far the largest plant in the field. Despite this difference in size within PI 164825, the plants were remarkably alike for other vegetative characters. This large PI 164825 plant was crossed with two lines that were growing in the greenhouse at Salinas: WMR 29 and I 5 a line from Bulgaria that carries the ms-4 gene. PI 134550 is another example. It had mean ratings of 4.5 for size and condition, but was rated 6 in one replication for both characters and rated 3 for both characters in the other replication. No crosses were obtained using this PI. Nineteen PIs had one or more plants in one or both replications that were more vigorous than most of the plants in the field; these PIs (marked with * in Table 1) should be investigated further for SPWF-P resistance.
Table 1. Mean plant sizez and mean plant conditiony of 151 wild melon Plant Introductions (PI) from India.
PI |
Size |
Cond. |
PI |
Size |
Cond. |
| 116479 | 3.0 | 3.0 | 123504 | 3.5 | 3.5 |
| 116482 | 3.0 | 4.5 | 123505 | 2.5 | 2.0 |
| 116487 | 2.0 | 2.5 | 123517 | 3.0 | 3.0 |
| 116489 | 2.5 | 3.5 | 123680 | 3.0 | 3.5 |
| 116490 | 3.5 | 3.0 | 123681 | 3.0 | 3.5 |
| 116459 | 3.0 | 2.5 | 123682* | 2.5 | 4.0 |
| 116660 | 4.0 | 5.0 | 123683 | 3.0 | 3.0 |
| 116661 | 2.5 | 3.0 | 123685 | 2.5 | 2.5 |
| 116664 | 3.0 | 3.5 | 123687 | 3.0 | 3.0 |
| 116667 | 2.5 | 2.5 | 123689 | 3.0 | 3.5 |
| 116736 | 3.0 | 2.5 | 123821 | 3.0 | 3.0 |
| 116738 | 2.5 | 2.5 | 123822* | 3.5 | 4.0 |
| 116824 | 3.0 | 2.5 | 123823 | 3.0 | 3.2 |
| 116826 | 3.0 | 3.5 | 123824 | 2.5 | 3.5 |
| 116827 | 3.0 | 3.5 | 124092* | 3.5 | 3.5 |
| 122828 | 3.5 | 4.0 | 124096 | 2.5 | 2.5 |
| 122847 | 4.0 | 3.5 | 124098 | 2.5 | 3.5 |
| 123187 | 2.5 | 2.5 | 124100 | 3.5 | 3.0 |
| 123188 | 3.0 | 3.0 | 124101 | 2.5 | 2.5 |
| 123493 | 2.0 | 2.5 | 124102 | 2.5 | 3.0 |
| 123494 | 2.5 | 3.0 | 124103 | 3.0 | 3.5 |
| 123495 | 2.5 | 2.5 | 124106* | 1.5 | 2.5 |
| 123496 | 2.5 | 2.5 | 124107 | 3.5 | 4.0 |
| 123498 | 2.5 | 3.0 | 124108 | 2.5 | 3.0 |
| 123499 | 2.0 | 3.0 | 124109* | 3.0 | 4.0 |
| 123500 | 3.5 | 3.5 | 124111 | 2,5 | 2,5 |
| 123501 | 2.5 | 3.5 | 124112 | 1.5 | 2.0 |
| 123502 | 3.5 | 4.5 | 124113 | 3.5 | 3.0 |
| 124114 | 3.0 | 3.5 | 164585 | 3.0 | 3.0 |
| 124206 | 3.0 | 3.0 | 164586 | 3.0 | 3.0 |
| 124208 | 2.5 | 3.0 | 164617 | 3.0 | 3.0 |
| 124210 | 2.5 | 2.5 | 164635 | 3.0 | 3.0 |
| 124214 | 2.5 | 2.5 | 164653 | 2.5 | 3.0 |
| 124429 | 2.0 | 2.0 | 164654 | 3.0 | 3.0 |
| 124431* | 3.5 | 3.5 | 164666 | 2.5 | 2.5 |
| 124436 | 3.0 | 3.5 | 164720 | 3.0 | 3.0 |
| 124439 | 3.0 | 3.0 | 164723 | 3.5 | 3.0 |
| 124440* | 2.5 | 2.0 | 164749* | 3.5 | 3.5 |
| 124441 | 2.5 | 2.5 | 164750 | 2.5 | 2.5 |
| 124443 | 2.5 | 2.5 | 164756 | 2.5 | 2.5 |
| 124447* | 2.0 | 3.0 | 164794 | 3.0 | 2.8 |
| 124449 | 2.5 | 3.0 | 164795 | 3.0 | 3.0 |
| 124550* | 4.5 | 4.5 | 164815 | 3.0 | 3.5 |
| 124552 | 2.5 | 3.5 | 164821 | 3.0 | 3.0 |
| 124553 | 4.0 | 3.5 | 164825* | 3.5 | 3.5 |
| 134196 | 2.5 | 3.0 | 164826 | 2.0 | 2.5 |
| 134199 | 2.5 | 3.0 | 164856 | 2.5 | 3.0 |
| 134200 | 3.0 | 3.5 | 165508 | 2.5 | 3.0 |
| 145594* | 4.5 | 5.0 | 165513 | 3.0 | 3.5 |
| 163206 | 2.0 | 3.5 | 165514 | 2.5 | 3.0 |
| 163208 | 3.0 | 3.0 | 165515* | 3.0 | 3.5 |
| 163211 | 2.5 | 3.5 | 165516 | 3.0 | 2.8 |
| 163212 | 3.0 | 3.5 | 165525* | 2.5 | 3.0 |
| 163219 | 2.5 | 3.0 | 166125 | 1.0 | 0.8 |
| 163220 | 2.0 | 3.0 | 173891 | 2.0 | 2.5 |
| 164179 | 2.0 | 3.0 | 174814 | 3.5 | 3.5 |
| 164270 | 2.5 | 3.0 | 174815 | 3.0 | 2.8 |
| 164320 | 3.0 | 3.5 | 175109 | 1.5 | 2.0 |
| 164323 | 3.0 | 3.2 | 179666 | 2.5 | 2.0 |
| 164327 | 2.5 | 2.5 | 179668 | 2.5 | 2.5 |
| 164329 | 2.5 | 2.5 | 179669* | 2.5 | 2.0 |
| 164330 | 2.5 | 3.0 | 179670 | 3.0 | 3.0 |
| 164331 | 2.5 | 3.0 | 179671* | 3.5 | 2.5 |
| 164343 | 3.0 | 3.5 | 179672 | 2.5 | 3.5 |
| 164400 | 2.0 | 3.2 | 179674 | 2.0 | 2.0 |
| 164409 | 3.0 | 3.5 | 179677 | 2.5 | 2.5 |
| 164466 | 2.5 | 2.5 | 179888 | 2.0 | 2.5 |
| 164479 | 2.0 | 2.0 | 179890* | 2.5 | 2.5 |
| 164481 | 2.0 | 2.5 | 179891 | 3.0 | 3.0 |
| 164487 | 2.0 | 2.0 | 179892 | 2.5 | 3.0 |
| 164492 | 2.5 | 2.5 | 179893* | 3.5 | 3.5 |
| 164493 | 1.0 | 2.0 | 179894 | 3.0 | 4.5 |
| 164551 | 3.5 | 4.0 | 179895 | 2.5 | 3.0 |
| 164569 | 2.5 | 3.0 | 179896 | 3.0 | 3.0 |
| 164583 | 2.5 | 2.5 | 179899 | 2.5 | 2.5 |
z Size was rated on a 1 (very small, only a few true leaves) to 9 (completely covering the bed) scale.
y Condition was rated on a 1 (dead) to 9 (vigorous, flowers) scale.
* PIs that should be investigated further for SPWF-P resistance.
Literature Cited
- Cohen, S., J.E. Duffus, and H.Y. Liu. 1992. A new Bemisia tabaci biotype in the southwestern United States and its role in silverleaf of squash and transmission of lettuce infectious yellows virus. Phytopathology 81: (in press).
- Culotta, E. 1991. “Superbug” attacks California crops. Science 254:1445.
- Duffus, J.E., R.C. Larsen, and H.Y. Liu. 1986. Lettuce infectious yellows virus – a new type of whitefly-transmitted virus. Phytopathology 76:97-100.
- Natwick, E.T. 1991. Spring, sweetpotato whitefly problems. Pest-O-Gram, University of California, Cooperative Extension, Imperial County, May 27, 1991.
- Oltman, D. 1991. In the wake of the whitefly. California Farmer, December 7, 1991:6, 7, 26.
- Perring, T.M., A Cooper, D.J. Kazmar, C. Shields, and J. Shields. 1991. New strain of sweetpotato whitefly invades California vegetables. California Agriculture 45 (6): 10-12.