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Healthy Fruit 1997 Vol. 5:12

Jul 16, 1997

Apple Maggot Fly Into Orchards

Apple maggot fly emergence from the soil is progressing, and captures on sticky red monitoring spheres are increasing as well. Most monitored orchards do have AMF present on spheres, but numbers remain relatively low at this point. Thus far only a couple of orchards have exceeded the recommended treatment threshold of 2 AMF per trap. Most areas of the state have received enough rainfall to trigger AMF emergence, so a late year on the AMF front is probably not in order. We believe that most orchards will reach treatment threshold levels during this next week, sparking the first AMF spray. As discussed in previous issues of Healthy Fruit, the most effective materials for use against AMF remain Guthion and Imidan.

European Red Mite Management All Over the Map

Among orchard blocks treated just before or soon after bloom with a miticide in conjunction with oil, those treated with either Savey or Agrimek are faring somewhat better than those treated with Apollo. In several orchards, there may be hotspots of mite multiplication without regard to the early-season treatment used. These infested areas may require a local treatment with a summer miticide (Pyramite or alternative).

To add to the mix, there are some orchards which received only oil as the early-season mite control program which have shown no pest mite activity as yet. Given this information, it is not easy to paint a general picture which indicates that use of early-season acaricides provides better overall results than use of oil alone. In fact, the opposite has been observed in some orchard blocks. This may be more as a consequence of the types of fungicides and insecticides used than the result of the ERM treatment program itself.

Early bronzing has appeared in some blocks of Red Delicious, which merits careful examination and treatment before the problem gets out of hand. In areas where Pyramite has been applied, early results indicate that the material is performing well. The season's first predaceous mites were also observed this week.

Leafminer Trek: The Next Generation

Second generation sap-feeding mines continue to develop; no tissue-feeding mines of the second generation have been observed as yet. Earlier sites should show evidence of these tissue-feeding mines this week. Perhaps the only LM treatment alternative which is available and effective at this point is Lannate, as the window for use of Provado against the second generation has gone by.

Leafhoppers Burn Young Trees

The biggest observed problem on the leafhopper scene continues to be the potato leafhopper. Shoots in untreated blocks are beginning to show burning along leaf margins; evidence of PLH infestation. We encourage growers to pay particular attention to young, non-bearing trees, which do not generally receive a standard insecticide routine. As mentioned in recent issues of Healthy Fruit, treatment with Sevin or Thiodan should aid in substantially reducing LH populations.

Wild, Woolly and Green

Across the state, woolly apple aphid infestation is beginning to appear on shoots, which warrants close monitoring. If WAA are allowed to build to substantial populations, the excrement produced by the aphids can give rise to the development of sooty mold fungus. In the past, a half-rate of Thiodan has provided good control.

Green apple aphids have developed to significant population levels in some orchards. Predation of GAA is beginning to take hold in areas of moderate to high populations, and it appears that reliance on the predators rather than treatment will again suffice for GAA control.

Peach Mites and Pear Psylla

Many peach blocks within the state have had significant problems with mites this year. In these areas with persistent mite populations, Vendex has worked well thus far.

Pear psylla populations are developing rapidly in the heat of the past couple of weeks, with sustained development even in blocks treated with Agrimek or Provado. In early trials, Pyramite has performed poorly at the labeled rate; no significant reduction of psylla development was seen.

Peach Fruit Rot Fungicides

The table below shows a list of peach fungicides effective against fruit rot. Remember a couple of points:

  1. All peach fruit rot is not brown rot. Some is Rhizopus rot, and if you have enough Rhizopus, and are not using a fungicide that can control it, the rot won't stop.
  2. Elite, Orbit and Indar are the premier brown rot fungicides. If you want to stop a problem, try one of these.

As fruit start to ripen, rots will, as always, take off. Be ready.

Fungicide Rate per 100 gallon dilute Brown rot Rhizopus rot
Benlate 50W + Captan 50W 4 - 6 oz. +

1 - 2 lb

Benlate 50W +Sulfur 95W 4 - 6 oz +

3 - 6 lb.

Botran 75W + Captan 50W 1 lb. + 1 lb. G G
Captan 50W 2 lb. G S
Elite 45 DF 2 oz. E+ -
Funginex 1.6E 12 - 16 fl. oz. E N
Indar 2 oz. per acre E+ -
Orbit 3.6E 4 fl. oz. per acre E+ S
Rovral 50W 2 lb. per acre E F
Ronilan 50W 12 - 16 oz. E N
Sulfur 95W 6 lb. G S
Topsin-M 70W + Captan 50W 4 - 6 oz. + 1 - 2 lb. E S
Topsin-M 70W + Sulfur 95W 4 - 6 oz. + 4 - 6 lb. E S

Rating scale: E = excellent, generally good disease control under heavy disease pressure; G = good, good control under moderate disease pressure; F = fair, fair control under moderate disease pressure; S = slight, some control under light disease pressure; N = little or no effect on indicated disease; - = information lacking or not applicable.