SLUG CONTROL OPTIONS IN STRAWBERRIES
(adapted from Michigan State University)
Slugs can cause serious damage to ripe fruit, especially in damp, cool weather. A recent study compared the standard Deadline Bullets slug bait product with a fairly new product called Sluggo which contains iron phosphate as the active ingredient. Unlike Deadline, Sluggo bait is light brown in color making it less visible to pickers, and it is also biodegradable and safe to humans, animals, and natural enemies. The two products were compared at a farm and in a replicated field trial. Deadline Bullets at 25 lb per acre provided excellent control of slugs over the month-long period between application and harvest, and reduced damage to harvested fruit by 95 percent, compared to the untreated areas. Sluggo at 40 pounds per acre did not significantly reduce slug populations, but it did provide protection of berries from slug damage (79 percent control), that was not significantly different from Deadline Bullets. It seems that the Sluggo has a less rapid toxic effect, but it does stop the slugs from feeding, which eventually leads to their death.
FUNGICIDES AND RAIN
(adapted from Purdue Extension)
Growers often ask whether one should apply fungicides before a rain. The fear is that the fungicide will wash off in the rain, leaving the plants with no protection. As a general rule, if the fungicide will dry on the foliage before the rain starts, go ahead and begin the applications. In most cases, the fungicide will dry within 30 minutes of application. If one waits for the rain to pass before spraying, much of the benefit of the fungicide will be lost. Rainy weather is the time when vegetable leaves are most in need of protection against fungal diseases. Most fungal diseases need rain to splash the spores from leaf to leaf; wet leaves are necessary for the spores of fungal diseases to start infection. (One exception to this rule is powdery mildew, which does not need rain for spread or to start infection.).
If a fungicide application is made before a rain, the spores that are splashed during the rain will be more likely to land on a leaf with good fungicide coverage. Similarly, it is not necessary to apply fungicides again every time it rains. It is best to maintain a schedule and keep to it. For most situations, maintain a 7 to 14 day fungicide schedule. Apply fungicides more often during rainy periods or when heavy dews occur. Fungicide applications can be spread out during drier periods. Fungicides do not have to be visible on leaves in order to offer protection.
SCOUT FOR SPIDER MITES
(adapted from UMass Extension)
Spider mites are small and hard to see, so the damage they cause often comes as a surprise. To control mites in a timely manner, growers should scout nightshade, cucurbit, small fruit and other crops by checking undersides of older leaves for the mites using a 10x hand lens. Infestations often start in drier dusty areas along field edges or roads, or around barns, fences, trees, or other obstacle acting as a windbreak. Mites can also be severe pests in the greenhouse. Two-spotted spider mite female adults have a pale yellow green or red oval body with pale legs and a dark green spot on either side of the body, which gives the mite its name. Nymphs may not have spots. All life stages spin webbing over the foliage, which protects the spider mites from predators, pesticides, and water loss. Mites also migrate by spinning a long strand of silk and ballooning on the wind. The European red mite also attacks vegetables and fruits. Adult females are brick red with several white bristles on their back.
Mites injure foliage by piercing and sucking, causing leaves to become blotched with pale yellow, reddish brown spots on both upper and lower leaf surfaces. If infestation is severe, leaves become pale and sickly in appearance, gradually die. On fruit or pods, symptoms include off-color spots or warty growths (tomato), pod drop (beans), and fruit curvature of the fruit (okra, melons etc.). A good indicator of spider mite buildup is often the presence of bleached out looking nightshade plants at field margins and waste areas. Spider mites reproduce rapidly under favorable conditions, and control can be difficult. See the New England Vegetable Management Guide for spray recommendations. Biological control with predaceous mites is a viable option for greenhouse crops if initiated before the pest population builds up. Amblyseius fallacies is an effective mite predator which is commercially available. If chemical control is deemed necessary, care must be taken to select an appropriate miticide and thoroughly cover the plants. A second application should be applied 5 to 7 days later to kill recently-hatched nymphs before they reach maturity and lay eggs for a new generation.
MONITORING FOR BLUEBERRY MAGGOT FLY
(adapted from Michigan State University)
Because the maggots of this pest develop inside the fruit, there is zero tolerance for infestation. To ensure that the first Blueberry Maggot Flies are detected, growers should deploy monitoring traps. Yellow Pherocon AM sticky boards are recommended for monitoring early in their activity season (about now in Vermont). These traps should be hung in a V shape in the top of the blueberry bush, with the yellow side facing downwards. Twist ties can be used to hold the trap in this position, and leaves should be cleared from the area near the trap to prevent contamination and to allow flies easy access to the trap. Check the traps at least once per week. Any blueberry maggot fly caught on the trap should be counted, recorded and removed. These flies have an inverted W pattern on their wing, and this should be identified before counting so only the pest insects are being counted.
For maximum effectiveness, the yellow boards must be recoated or replaced after three weeks of exposure. To increase fly attraction to traps, they should be baited with ammonium acetate or ammonium carbonate baits. Traps can be purchased with bait mixed into the sticky coating, or the regular yellow traps can have “superchargers” added to them (small yellow plastic containers) that release the odors to attract flies. A supercharger should be hung with each trap and should be replaced or refilled periodically according to the instruction. In commercial highbush blueberry operations, a minimum of two Pherocon AM boards are needed every 5 acres. One trap should be placed in the field adjacent to wild host plants, and the other trap should be placed in the center of the five-acre block. This will allow detection of fly populations that move into the field versus those resident in the field. If flies are trapped immediately after they emerge from the soil, there is a 7 to 10 day period before egg-laying begins. Because of this, if flies are trapped the first insecticide treatments should be timed for within a week after the first fly captures. This maximizes the impact of the treatment against egg-laying flies to prevent fruit infestation.
Sticky green spheres may also be used for monitoring blueberry maggot fly. However, these traps are more effective later in the season when the majority of the flies have attained sexual maturity. Sticky spheres should be placed within the bush approximately six inches from the top of the bush and baited.
SQUASH VINE BORER IN PUMPKINS AND SQUASH
(adapted from Purdue Extension)
SVB is an occasional pest of pumpkins and squash in our area. The adult borer is a “clear wing” moth with wingspan about 1.5 inches. Their front wings are metallic green, and the rear wings are almost without scales. The body is generally orange-red with black bands on the abdomen. The moth is a daytime flier, and is commonly mistaken for a wasp. Symptoms of plants attacked by the borers appear in mid-summer when a runner or an entire plant turns yellow or wilts suddenly and the infested vine usually dies beyond the point where the borer tunneled into the stem. The presence of the borer is usually not noticed by growers until after the damage is done. Damage is usually worse in areas where squash and pumpkins are grown year after year.
The eggs of the borer, which are small and brown, are usually laid singly at the base of the plant, on the petioles of leaves, on the stems, or occasionally on the surface of leaves. The eggs will hatch within a few days. The squash vine borer larvae bore into the plant immediately after hatching. As the larvae bore into the stem, they leave behind a telltale sign of sawdust-like frass at the entrance hole. The larvae, which are white grub-like caterpillars, feed inside the stem for 2 to 4 weeks. The larvae destroy the vessels in the stems, causing the vines to wilt and eventually die. Once inside the vine, little can be done to control the pest. After they are full-grown, the larvae leave the vine and spin silken cocoons in soil.
PHOMOPSIS DISEASE IN BLUEBERRY
(adapted from Rutgers Extension)
Phomopsis has been seen in some areas. All varieties show symptoms
but Weymouth, Bluecrop, Blueray and Berkeley seem to be the most affected.
Dieback of twigs and canes may become more severe as warm weather occurs
and as strain of producing a crop further weakens the wood. Twig blight
symptoms usually consist of a tip dieback of about 2 to 6 inches on current-year
wood. Small black pycnidia may also be produced upon the blighted twigs.
As with other canker disease, the most conspicuous symptom is the "flagging,"
or wilting and death of individual stems during the summer. Under severe
disease conditions, several individual canes may be affected on a single
bush. When Phomopsis canker is responsible for this symptom, the actual
infection site appears as an elongated flattened area, usually near the
base of the cane. Small black dots that are the spore-containing bodies
(pycnidia) of the Phomopsis fungus can sometimes be seen within this flattened
area. Pruning the weakest canes to the ground may not seem practical from
the standpoint of labor and costs but it is the best practice for the long-term
production of the bush. Winter injury, compounded by Phomopsis, often causes
poor production for two successive years if some radical pruning is not
done early during the first growing season of the injury. Fungicide sprays
are a help early but
do little good at this time.
Mention of pesticides is for information purposes only, no endorsement is intended nor is discrimination against products not mentioned. Always read and follow the label.
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