Spring-Summer, 1988

 An unreplicated trial was planted on April 6, 1988, using five varieties: Station Vine, King Crown, Manicou,
Antigua and Santo Domingo. Vine cuttings 30-38 cm In length were planted at a 1 m row spacing anda 50cm plant
spacing within rows. Rows were 10 m long, and each variety was planted In three-row plots.
 The plots were drip-Irrigated to ensure good crop establishment and development. The crop was harvested on
September 1, 1988, approximately five months after planting.
 Total yields ranged from 11.5 to 36.3t ha-' (Table 15). Santo Domingo produced the highest total yield, followed
by Station Vine. Manicou produced the lowest total yield. Marketable yields ranged from 1.3 to 6.31 hae. Low
marketable yield was attributed to weevil damage which reached up to 94 percent of the crop in variety Station Vine.
No variety showed resistance to weevil infestation, but King Crown had less than 60 percent weevil damage.
 This unreplicated trial indicates that the weevil is a major pest of sweet potato and screening varieties for
resistance and evaluating effective control methods should be given high priority.

 Table 15. Total and marketable tuber yield of sweet potato
 varieties grown during spring-summer, 1988, at UVI-AES.

 Yield (t ha-') Marketable Weevil Damage
 Variety Total Marketable yield (%) (%)

 Santo Domingo 36.3 6.3 17.4 82.1
 Station Vine 21.1 1.3 6.2 93.8
 Antigua 19.5 3.8 19.5 80.5
 King Crown 11.8 6.1 51.7 48.3
 Manicou 11.5 4.0 34.8 65.2

 Note: Weevil damage is based on marketable yield.


 During the same growing season a replicated trial was conducted using ten entirely different varieties. The trial
wasplantedon May 6,1988. Vine cuttings 30-40 cm in length were planted in three-row plots 6 m long. Plant spacing
was 1 m between rows and 50 cm between plants within rows. A randomized complete block design was used with
three replications. The crop was harvested on September 23, 1988.
 There were differences in yield and weevil damage among varieties (Table 16). In general, both total and
marketable yields were low, ranging from 0.2 to 16.6 t ha' and 0.2 to 7.1 t ha-', respectively (Table 16). Twelve Prime
was the highest-yielding variety. Weevil damage was greater than 50 percent in five varieties. Varieties EAS 10 and
Mont Blanc were highly susceptible, while Trompo Negro and St. George appeared to be resistant. The results of
this trial indicate that Twelve Prime and Trompo Negro are promising sweet potato varieties for the Virgin Islands.

 Table 16. Total and marketable tuber yield of sweet potato varieties
 grown during spring-summer, 1988. at UVI-AES.

 Yield (t ha') Marketable Weevldamage'
 Variety Total Marketable yield (%) (%)

 Twelve Prime 16.6 a 7.1 a 46.4 55.9 ab
 Mont Blanc 7.4 b 1.7 b 23.0 80.2 a
 Trompo Negro 6.0 bc 5.3 a 88.3 7.4 b
 EAS 15 3.7 be 2.2 b 59.2 49.9 ab
 EAS 13 3.6 bc 2.6 b 72.2 38.2 ab
 EAS 10 3.5 bc 1.3 b 37.1 72.2 a
 Black Rock 3.2 bc 1.8 b 56.3 51.2 ab
 Ninety Nine 1.8 c 0.8 b 44.4 79.6 a
 St. George 0.6 c 0.4 b 66.7 11.1 b
 Margarita 0.2 c 0.2 b 100.0 33.3 ab

 'Means within a column followed by the same letter are not significantly
 different by Duncan's Multiple Range Test, (P=0.05).