Biomedical Engineering Reference
In-Depth Information
Cuphea Diseases and Insects
The only disease reported for cuphea is white mold (
Sclerotinia sclerotiorum
(Lib.)
De Bary.), which caused patches of dead plants in tests plots at Morris, MN, and
Prosper, ND, in 2004. A yield reduction as high as 85 % was found in affected areas
compared with that of non-diseased cuphea fields [
78
].
Seedling blight and damping-off of cuphea was observed in several fields in
North Dakota and Minnesota between 2004 and 2006. The efficacy of several
fungicide seed treatments was evaluated in several experiments in the field and
greenhouse between 2005 and 2007 [
11
]. According to the results of this study, the
superior efficacy of mefenoxam over other fungicides seed treatments indicates that
a pathogen from the Oomycetes class, such as
Pythium
or
Phytophthora
, is likely
responsible for the seedling blight and damping-off symptoms. Treating cuphea
seeds with mefenoxam (0.15 g a.i. kg
1
seed) is highly recommended to improve
seedling establishment. This is especially important in fields that have had sugar
beet (
Beta vulgaris var. saccharifera
L.) grown in the past.
Few insects feed on cuphea plants due to the stickiness of the plant stems, leaves,
and flowers. Small insects such as several aphids' species and the insidious flower
bug (
Orius insidiosus
(Say)) die after becoming stuck to the plants [
79
]. A study to
determine if cuphea would reduce western corn rootworm (
Diabrotica virgifera
virgifera
Le Conte) populations in corn-soybean rotation when cuphea was grown
following the corn (
Zea mays
L.) crop indicated that larvae of the western corn
rootwormmay be able to complete their cycle in cuphea fields by feeding on cuphea
roots. Behle and Isbell [
79
] concluded that it is unlikely that cuphea would greatly
reduce corn rootworm populations, thus, reducing damage on the following corn
crop, but they also suggested that more research is needed to confirm this. Larvae of
corn earworm (
Helicoverpa zea
L.) caused extensive damage in cuphea in Peoria,
Illinois, in 2006 (T. Isbell, personal communication). Gall-inducing insects (many
species) have been observed in ornamental species of
Cuphea
,
C. appendiculata
,
C. cyanea
,
C. hookeriana
,
C. llavea
,
C. nitidula
, and
C. spectabilis
[
80
].
Cuphea Harvest
An important factor in determining when to harvest crops is seed moisture. Gener-
ally, seed moisture at harvest is high for cuphea because mixtures of seeds at
different stages of maturity occur at harvest due to the indeterminate growth habit
of the plant [
7
,
25
]. For any crop, as its seed reaches physiological maturity, seed
moisture decreases [
11
,
64
]. Seed moisture of cuphea at physiological maturity
(30 days post anthesis) fluctuated between 62 and 156 g kg
1
in a study conducted
in North Dakota [
11
]. Although in cooler seasons, seed moisture at physiological
maturity might be as high as 449 g kg
1
[
81
]. Greatest seed yields were obtained
when cuphea was harvested in late September to early October, 139-147 days from
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