I think the rose developed rose canker. I have had several roses with this problem. The solution is to prune back to where you see only green canes and then treat with lime and sulfur solution. That has worked for me-it is sold at Ace Hardware store or Home Depot. Make sure you sterilize the pruner after use.
Pitting resistance equivalent number (PREN) is a measurement of the corrosion resistance of various types of stainless steel.Exact testing procedures are specified in the ASTM G48 standard. In general: the higher PREN-value, the more corrosion resistant the steel.The PREN-value is calculated using the following formula: PREN = 1 x %Cr + 3.3 x %Mo + 16 x %N (w/w) Steels with PREN-values above 32 are considered seawater (corrosion) resistant.urthermore a PREN-value â¥ 40 for duplex steels is called for in the DIN EN ISO 15156 as well as the American NACE â a standard for use in hydrogen sulfide environments known in the oil and gas extraction industries. Exception: stainless steels with molybdenum content â¥ 1.5% may have a PREN-value â¥ 30.
Only then will the proposal be accepted and work on the standard can begin. If there is an existing International Standard on the subject, it will be adopted, unchanged, as the European Standard. If this is not the case, the responsible working body will draw up a manuscript for the draft standard (prEN).he draft standard is then made available to all ISO (or IEC) members, who have three months to submit their national position and comments. In Germany, the responsible working body can decide to publish a German-language draft of a DIN ISO Standard or DIN IEC Standard.